Muhammad (pbuh) believed that there was only one Allah, Creator of the sun, the moon, the earth, the sky, and of all living things, and that all people should worship only Him. Muhammad (pbuh) would often leave the crowded city and go to the cave in Mount Hira'. He liked to be alone there, away from all thoughts of the world and daily life, eating and drinking little. In his fortieth year, Muhammad (pbuh) left Mecca to spend Ramadan,
The traditional month of retreat, in the cave. In the second half of Ramadan, Allah began to reveal His message for mankind through Muhammad (pbuh). This first Revelation occurred as follows. The Archangel Gabriel came to Muhammad (pbuh) in the cave and commanded him to 'Read'. Muhammad (pbuh) replied 'I cannot read.' At this the Archangel took Muhammad (pbuh) in his arms and pressed him to him until it was almost too much to bear. He then released him and said again 'Read.' 'I cannot', replied Muhammad (pbuh), at which the Archangel embraced him again. For the third time the Archangel commanded Muhammad (pbuh) to read, but still he said he could not and was again embraced. On releasing him this time, however, the Archangel Gabriel said:
"Read: In the Name of thy Lord who createth, Createth man from a clot. Read: And thy Lord is the Most Generous Who teacheth by the pen, Teacheth man that which he knew not. (Al Quran 96:1-5) Muhammad (pbuh) repeated these verses, just as the Archangel had said them.
When the Archangel was sure Muhammad (pbuh) knew them by heart, he went away. Now that he was alone Muhammad (pbuh) could not understand what had happened to him. He was terribly afraid and rushed out of the cave. Perhaps the cave was haunted? Perhaps the devil had taken a hold of his mind? But he was stopped by a voice from heaven which said; O Muhammad (pbuh) you are the Messenger of Allah, and I am Gabriel.' He looked up at the sky and wherever he turned he saw the Archangel Gabriel.
In a state of confusion he returned home to Khadijah. When his wife saw him she became very worried as he began to shiver, as though in a fever. He asked her to wrap him in blankets, which she did. After a while he recovered sufficiently to tell her what had happened at Hira'. Khadijah believed all that he told her and with great respect said: 'Be happy, 0 son of my uncle and be confident. Truly I swear by Allah who has my soul in His hands, that you will be our people's Prophet.' Muhammad (pbuh),
the Messenger of Allah, was eased by her faith in him, but after all that had happened he was exhausted and felt fast asleep.
Khadijah left the Prophet (pbuh) sleeping and went to see her cousin, Waraqah Ibn Nawfal, to ask him what he thought about all that had happened. Waraqah was a very wise man who had read many books and had become a Christian after studying the Bible. He told Khadijah that Muhammad (pbuh) had been chosen by Allah to be His Messenger. Just as the Archangel Gabriel had come to Moses before and had ordered him to guide his people, so, too, would Muhammad (pbuh) be the Prophet of his people. But Waraqah warned that all the people would not listen to the Prophet and some would mistreat his followers. He must, however, be patient because he had a great message for all the world. From that day on, the Archangel Gabriel came often to the Prophet (pbuh) and the verses he taught him, the message from Allah to man, were later written down, and are known to us as the Holy Koran.
After that momentous day in the month of Ramadan, Revelation came again and again to the Prophet (peace be upon him). He understood now what he had to do and prepared himself for what was to come. Only a strong and brave man, helped by Allah, can be a true prophet because people often refuse to listen to Allah's message. Khadijah (May Allah be pleased with her) was the first to believe the Prophet (peace be upon him) and accept as true what he brought from Allah. Through her, Allah made things easier for the Prophet (peace be upon him). Khadijah strengthened him, helped him spread his message, and stood up to the people who were against him.
Then Revelation ceased for a time. The Prophet (peace be upon him) was upset and unhappy, thinking that Allah had left him, or that he might have angered Allah in some way so that Allah no longer thought him worthy of His message. However, the Archangel Gabriel came back to him and brought this surah, or chapter, of the Koran:
"By the morning hours,And by the night when it is stillest, Thy Lord hath neither forsaken thee nor doth He hate thee, And verily the Last will be better for thee than the First. And verily thy Lord will give unto thee so that thou wilt be content. Did He not find thee an orphan and protect thee? Did He not find thee wandering and guide thee? Did He not find thee destitute and enrich thee? Therefore the orphan oppress not, Therefore the beggar drive not away, And as for thy Lord's blessing, declare it". (Al Quran 93:1-11)
The Prophet (peace be upon him) began to speak secretly of Allah's message to those Who were close to him and whom he could trust. At that time Mecca was going through hard times. There was very little food to be had. Abu Talib, the Prophet's uncle, who had taken care of him after his grandfather's death, was finding it very difficult to feed his large family.
The Prophet (peace be upon him) said that he and another uncle, al-'Abbas, who was a rich man, would each bring up one of Abu Talib's children in order to help him. The Prophet (peace be upon him) took 'Ali and his uncle took Ja'far.
One day, when the Prophet (peace be upon him) was outside the city, the Archangel Gabriel appeared to him. The Archangel kicked the side of a hill and a spring of water began to flow out. He then began to wash himself in the running water to show the Prophet (peace be upon him) the ritual ablution to be made before prayer. Then the Archangel showed him all the positions of Muslim prayer-the various movements and things to be said with each movement. The Prophet (peace be upon him) returned home and taught all these things first to Khadijah and then to his followers. Since then Muslims have continued to purify themselves before prayer by performing the ritual ablution and have followed the same movements and prayers first performed by the Prophet (peace be upon him). To begin with, though, only the Prophet (peace be upon him) and his wife knew of these things. Then one day 'Ali entered the room and found the Prophet (peace be upon him) and Khadijah praying.
He was puzzled and asked what they were doing. The Prophet (peace be upon him) explained to him that they were praising Allah and giving thanks to Him. That night 'Ali stayed up thinking about all that the Prophet (pbuh) had said; he had great admiration and respect for his cousin. Finally he came to a decision and the next day he went to the Prophet (peace be upon him) and told him that he wanted to follow him. Thus Khadijah was the first woman to embrace Islam, the teachings which the Prophet (peace be upon him) brought from Allah, and 'Ali was the first young man. Shortly after they were joined by Zayd ibn Harithah, a slave, freed and adopted by the Prophet (peace be upon him).
The Prophet (peace be upon him) began to leave Mecca with Ali in order to pray. One day Abu Talib happened to pass by and when he saw them he stopped and asked them what they were doing. The Prophet (peace be upon him) told him that they were praying and following the same religion as Abraham. He explained that, like Abraham, he had been ordered to guide the people to Allah's truth. Abu Talib looked at his son, 'Ali, and said: 'Muhammad (peace be upon him) would never make you do anything that was wrong. Go with him. But I cannot leave the religion I now follow and which was followed by my father.'
Then he turned to the Prophet (peace be upon him), saying, 'Even so, I promise you, Muhammad (peace be upon him), that no one will hurt you as long as I am alive.' And with that Abu Talib went on his way. At about this time the news of Muhammad (peace be upon him) being the Prophet reached an honest, wise, and respected merchant of Mecca called Abu Bakr (May Allah be pleased with him). He knew Muhammad (peace be upon him) well and believed he could never lie, so he went to find out for himself if the story were true. The Prophet (peace be upon him) told him that he had indeed been sent by Allah to teach everyone to worship the one true Allah. On hearing this from the Prophet's own lips Abu Bakr knew it to be the truth and became a believer instantly. Later the Prophet (peace be upon him) was reported to have said that everyone he ever invited to accept Islam showed signs of disbelief and doubt, except Abu Bakr; when he was told of it he did not hold back or hesitate.
Because of his wisdom, honesty, and kindness people had always turned to Abu Bakr for advice. He was, therefore, a man of some influence and through him many people came to Islam. Among these was Sa'd ibn Abi Waqqas as, the uncle of Aminah, the Prophet's mother. The night before Abu Bakr came to visit him and tell him about Islam, Sa'd Ibn Abi Waqqas dreamt that he was walking in darkness. As he walked he saw the moon and when he looked at it he saw 'Ali, Abu Bakr, and Zayd, the Prophet's freed slave, beckoning to him to come and join them. When Abu Bakr told him about the Prophet's religion, he understood the meaning of his dream and went at once to the Prophet (peace be upon him) and declared himself a Muslim. He understood that to be a Muslim means to submit oneself to Allah's Will and to serve only Him. Another person brought to Islam by Abu Bakr was Bilal. One night Abu Bakr went to the house of Umayyah ibn Khalaf, one of the most important men of Quraysh. Umayyah was out and Abu Bakr found only Umayyah's slave, Bilal, at home. Abu Bakr talked to the slave about Islam and before he left, Bilal, too, had become a Muslim. The number of people following the Prophet (peace be upon him) began to grow. Sometimes they would all go out of the city to the mountains around Mecca to hear him recite the Quran and to be taught by him. This was all done very secretly and only a very few people knew about Islam in those early days.
Three years passed and one day the Archangel Gabriel came to the Prophet (peace be upon him) and ordered him to start preaching openly to everyone. So the Prophet (peace be upon him) told the people of Mecca that he had something very important to tell them. He stood on a hillside in Mecca, called Safa, and they gathered around to hear what he had to say. He started by asking them if they would believe him were he to say that an army was about to attack them. They answered that indeed they would, because he never lied. He then told them that he was the Messenger of Allah, sent to show them the right way, and to warn them of terrible punishments if they did not follow him in worshipping only Allah and none other. Abu Lahab, one of the Prophet's uncles who was among the listeners, suddenly stood up and said, 'May you perish! Did you call us here just to tell us this?' At this, Allah sent to the Prophet (peace be upon him) the following Surah:
"The Power of Abu Lahab will perish, and he will perish. His wealth and gains will not save him. He shall roast at a flaming fire, And his wife, the carrier of firewood Will have upon her neck a rope of palm-fibre". (Al Quran 111:1-5)
Then the crowd dispersed and the Prophet (peace be upon him) was left alone. A few days later the Prophet (peace be upon him) tried again. A feast was prepared in his house for all of his uncles. After the meal he spoke to them and said, 'O sons of 'Abd al-Muttalib! I know of no Arab who has come to his people with a better message than mine. I have brought you the best news for this life and the next.
Allah has ordered me to call you to Him. So which of you will help me?' All the men kept silent. Then 'Ali, his cousin, jumped up and said: 'O Prophet of Allah! I will help you.' Then the men all got up and left, laughing as they went because only one young boy had agreed to help the Prophet (peace be upon him).
His message ignored by most of the people and his uncles, the Prophet (peace be upon him) continued to meet his friends secretly in a house near the hill of Safa. There they prayed together and he taught them about the religion of Islam. But even though they kept to themselves, they were sometimes abused by those who would not believe. From one such incident, however, an unexpected conversion to Islam took place. One day, when the Prophet (peace be upon him) was returning home, speaking with his followers, he met Abu Jahl, a leader of Quraysh, who hated the Prophet (peace be upon him) and his teachings. Abu Jahl started to insult him and to speak spitefully of Islam, but the Prophet (peace be upon him) made no reply and went on his way.
Later, Hamzah, one of the Prophet's uncles, who was a strong and brave warrior of whom people were quite afraid, heard how his nephew had been insulted. Filled with rage, he ran straight to the Ka'bah where Abu Jahl was sitting among the people and struck him a violent blow in the face with his bow. Hamzah then shouted, 'Will you insult him when I follow his religion, and I say what he says? Hit me back if you can!' Some people got up to help Abu Jahl but he stopped them saying, 'Leave Hamzah alone, for by Allah, I have insulted his nephew badly. 'From that moment on Hamzah (May Allah be pleased with him) followed the teachings of the Prophet (peace be upon him) and with his conversion to Islam Quraysh realized that the Prophet (pbuh) had a strong supporter and so for a while they stopped persecuting him. Soon, however, the leaders of Quraysh became angry again, when they saw that the Prophet (peace be upon him) was going ahead with his teaching. A group of them went to his uncle, Abu Talib, who had promised to protect him. They told him to ask the Prophet (peace be upon him) to stop attacking their gods and their way of life, and in return they would let him do as he wished with his religion.
After a time they saw that there was no change, so they went back to Abu Talib and this time they told him that if he did not stop his nephew, they would fight them both. Abu Talib was very upset by this quarrel among his people, but he could not break his word to his nephew. He sent for the Prophet (peace be upon him) and told him what had happened, saying, 'Spare me and spare yourself; do not put a greater burden on me than I can bear.' The Prophet (peace be upon him) thought that his uncle might abandon him and that he would no longer have his support, but nevertheless he answered, O my uncle, by Allah, if they put the sun in my right hand and the moon in my left in return for my giving up this cause, I would not give it up until Allah makes Truth victorious, or I die in His service. Abu Talib was deeply moved by this answer. He told the Prophet (peace be upon him) that he would support him for as long as he lived and encouraged him to go on spreading Allah's message.
From that time on, however hard the leaders of Quraysh tried to convince Abu Talib to stop protecting his nephew, he always refused to listen to them. In order to get rid of the Prophet (peace be upon him) and his followers, his enemies started persecuting those Muslims who were poor or weak, or had no powerful friends. One such person was Bilal (May Allah be pleased with him), the slave of Umayyah ibn Khalaf. His master would take him out into the desert, tie him up, and leave him in the sun with a large stone on his chest. Fortunately Abu Bakr(May Allah be pleased with him) was passing by one day and saw Umayyah torturing Bilal, so he bought him from his master for a large sum of money and then set him free. But not all persecuted Muslims were as fortunate as Bilal. Many suffered, but all of them endured it patiently, knowing that they were doing the right thing and that their reward in the life to come would be greater' than any happiness they could find on earth.Source
The Prophet (pbuh) and his followers went back to a normal way of life but the years of hardship had made Khadijah very weak.
She became ill and soon afterwards she died. Thus, the Prophet (pbuh) lost his beloved wife and friend, the first person to accept Islam and support him. She had been a refuge from all his troubles and, through her good-heartedness, the best company in his suffering. He had loved her very much. This happened in 619 A.D., the year which became known as the 'Year of Sorrow'. Soon after this, the Prophet Muhammad's uncle and protector, Abu Talib, also died. Abu Talib had been one of the most respected men in Mecca-one of the elders of Quraysh. Even though he had never been a follower of Islam, he had protected the Prophet (pbuh) against his enemies. Not only was this a sad occasion for the Prophet (pbuh) but also a dangerous one. According to Arab custom anyone who is under the protection of another is safe so long as his protector lives. Now, with the death of his uncle, the Prophet's protection was gone.
The Prophet's enemies rejoiced to see him so sad, without a wife to console and comfort him, and without his uncle to protect him. They began to treat him worse than ever before. Even small children insulted him. One young man actually threw some filth on the Prophet's head, but the Prophet (pbuh) went home without making anything of it. When one of his daughters rushed, weeping, to wash it away, he comforted her saying, 'Do not weep my little girl, for Allah will protect your father.' Abu Talib had been the Prophet's last tie with Quraysh and the Prophet (pbuh) now felt that Islam could make no further progress in Mecca because the hearts of Quraysh were closed against him. He decided, therefore, to travel to Ta'if where he hoped to find support. He walked all the way to the town, which was seventy kilometers away. There he spoke in all the places where people gathered, but no one listened to him. He met the leaders of the three most important tribes but they would not listen either. Not only did they take no notice of what he said,
but they laughed at him and ordered their slaves to insult him and pelt him with stones.
Sadly, the Prophet (pbuh) left the city and found a quiet place near a wall for Utbah & Shaibah sons of Rabiy'ah on the edge of town where he could be alone. There he prayed to Allah in these words: " O Allah, to Thee I complain of my weakness, helplessness and lowliness before men. 0 Most Merciful, Thou art the Lord of the weak, and Thou art my Lord. To whom wouldst Thou leave my fate? To a stranger who insults me or to an enemy to whom Thou hast given power over me? If Thou art not angry with me, I care not what happens to me. Thy favor alone is my objective. I take refuge in the Light of Thy countenance by which the darkness is illumined and on which this world and the other depend, lest Thy anger descend upon me or Thy wrath light upon me. It is for Thee to be satisfied until Thou art well pleased. There is no power and no might save through Thee." The wall near which the Prophet (pbuh) was sitting belonged to a garden owned by two brothers.
When they (the sons of Rabiy'ah) heard his prayer, they were very sorry for him and sent one of their slaves to him with a dish filled with grapes. Before he began to eat, the Prophet (pbuh) said 'Bismillah'-'In the Name of Allah.' The servant, whose name was 'Addas, was very surprised at these words, which he had never heard before. 'By Allah', said 'Addas, 'this is not the way the people of this country speak.' 'Then from what country do you come, 'Addas, and what is your religion?' asked the Prophet (pbuh). 'I am a Christian from the Assyrian town of Nineveh', he replied. 'From the town of that good man Jonah, son of Matta', added the Prophet 'How do you know about him?' asked 'Addas. 'He is my brother-he was a Prophet and I am a Prophet', answered the Messenger of Allah (pbuh). 'Addas bent down and kissed the Prophet's head, his hands and his feet, because now he saw that he was truly a Prophet. The Prophet (pbuh) then walked back to Mecca. He was now able to put up with everything patiently for he knew that Allah would never leave him.
His journey to Ta'if had not been in vain for 'Addas, the Christian, had become a Muslim, and this was to be the beginning of great changes.
Quoted from here with slight modifications
At the tenth year after Mohammad peace be upon him had became a prophet, Allah wanted to console his prophet especially after he lost his uncle Abu-Talib and Khadijah his kind and caring wife who was supporting him in his way of calling to Allah. One night as the Prophet (peace be upon him) lay sleeping in the same spot where 'Abd al-Muttalib used to sleep, next to the Ka'bah, he was woken by the Archangel Gabriel. Later the Prophet (peace be upon him) described what happened: 'I sat up and he took hold of my arm. I stood beside him and he brought me to the door of the mosque where there was a white animal for me to ride.'
The Prophet (peace be upon him) told of how he mounted the animal and, with the Archangel Gabriel at his side, was transported from Mecca to the mosque called al-Aqsa, in far away Jerusalem. There the Prophet (peace be upon him) found Abraham, Moses, and Jesus among a group of Prophets. The Prophet Muhammad (peace be upon him) acted as their leader, or imam, in prayer. Then he was brought two jugs, one containing wine and the other milk.
He chose the milk and refused the wine. At this, the Archangel Gabriel said, 'You have been rightly guided to the fitrah, the true nature of man, and so will your people be, Muhammad. Wine is forbidden to you. The Prophet (peace be upon him) also related how they passed through Heaven's gates and saw countless angels. Among them was Malik, the Keeper of Hell, who never smiles. Malik stepped forward and showed the Prophet (peace be upon him) a view of Hell and the terrible plight of those who suffer in that place. Then the Prophet (peace be upon him) was taken up by the angels, through the seven Heavens, one by one Along the way he again saw Jesus, Moses, and Abraham, and the Prophet (peace be upon him) said that he had never seen a man more like himself than Abraham. He also saw John, called Yahya in Arabic, Joseph or Yusef, Enoch, that is Idris, and Aaron. At last he reached the Lote Tree of the Uttermost, the sidrat al-muntaha where no Prophet had been before. Here the Prophet (peace be upon him) received Revelation of what Muslims believe.
"The Messenger believeth in that which hath been revealed unto him from his Lord and (so do) the believers. Each one believes in Allah and His Angels and His Books and His Messengers-We make no distinction between any of His messengers-and they say: We hear, and we obey. Grant us Thy forgiveness, our Lord. Unto Thee is the homecoming". (Al Quran 2:285)
Then he was taken into the Light of the Divine Presence of Allah, and was instructed that Muslims should pray fifty times a day. The Prophet (peace be upon him) recalled: " On my way back I passed by Moses and what a good friend to you he was! He asked me how many prayers had I been ordained to perform. When I told him fifty, he said, 'Prayer is a serious matter and your people are weak, so go back to your Lord and ask Him to reduce the number for you and your community.' I did so and He took away ten. Again I passed by Moses and he said the same again; and so it went on until only five prayers for the whole day and night were left.
Moses again gave me the same advice. I replied that I had been back to my Lord and asked him to reduce the number until I was ashamed, and I would not do it again. He of you who performs the five prayers faithfully, will have the reward of fifty prayers.
On the morning following these events and the Prophet's return to Mecca, he told Quraysh what had happened. Most of them said, 'By God! This is ridiculous! A caravan takes a month to go to Syria and a month to return! Can you do that long journey in a single night?' Even many Muslims were amazed by this and wanted the Prophet (peace be upon him) to explain. Some ran with the news to Abu Bakr who said, 'By Allah, if Muhammad (peace be upon him) himself has said so, then it is true. Remember, the Prophet tells us that the word of Allah comes to him directly from heaven to earth at any hour by day or night, and we believe him. Isn't that a greater miracle than what you are now doubting?
Then Abu Bakr went to the mosque and listened to the Prophet's detailed description of Jerusalem. He commented, 'You tell the truth, O Prophet of Allah!' From then on, Abu Bakr was honored with the title 'al-Siddiq', which means 'he who gives his word to support the truth'. Others also began to believe the Prophet's story when he went on to describe two caravans he had seen on his way back to Mecca. He told the doubters where he had seen the caravans, what they were carrying and when they would arrive in Mecca. All that the Prophet (peace be upon him) had said was born out when the caravans arrived at the time he said they would, carrying all that he had described.
"Glory be to Him, who carried His servant by night from the Holy Mosque to the Far distant place of worship, the Neighborhood which We have blessed, that We might show him some of Our signs, He, only He is the All-hearing, the All-seeing". (Al Quran 17:1)
By the Star when it setteth, Your comrade is not astray, neither deceived, Nor does he speak of his (own) desire. This is naught but a revelation revealed, Taught him by one mighty in power, very strong; he stood poised, being on the uppermost horizon, Then drew near and came down, two bows'-length away, or nearer, Then revealed to His servant that which He revealed. His heart lies not of what he saw; What, will you then dispute with him what he sees? Indeed, he saw him yet another time By the Lote- Tree of the utmost Boundary Near which is the Garden of Abode When there covered the Lote- Tree that which covered; his eye turne not aside, nor yet was overbold. Verily, he saw one of the greatest signs of his Lord.(Al Quran 52:1-18)
Quoted with slight modifications from here