He is the Last of God's Prophets

Muhammad (S.A.W.) was a child of eight when his grandfather, `Abdul-Muttalib, passed away. At the time of his death, `Abdul-Muttalib instructed his son, `Abu Talib, to take good care of Muhammad (S.A.W.) and to protect him, "Muhammad (S.A.W.) is an orphan who has been denied the blessings of a mother and a father", he said "I entrust him to you for you to protect him and guard him well. He has a brilliant future and will obtain a great, position."
Abu Talib accepted his father's instructions and took charge of Muhammad (S.A.W.) as directed, and cared for him like a loving father.
Muhammad (S.A.W.) was about twelve years old when he accompanied his uncle, Abu Talib, on a journey to the city of Damascus with a trading caravan of the Quraysh. For a child of twelve like Muhammad (S.A.W.) this journey was tough and difficult, but looking at the wonders and beauties of nature, the mountains and plains, reduced for him the weariness and hardship. For Muhammad (S.A.W.) seeing the great wide deserts, the highlands and the lowlands, the towns and the 
villages, was very enjoyable.
The caravan arrived near the town of "Basra". At that place there was a house of worship that had been built from ancient times, in which there was always one of the wise men of the Christians engaged in worship, waiting to see the Last Prophet of God. The Prophet `Isa and the previous prophets had told about the coming of "the Last Prophet of God" and about his special signs.
That house of worship was called "Dayr" and at that time "Buhayra" was living there engaged in worship As the caravan came into view from a far ,Buhayra came out of Day and witnessed things that amazed him. The caravan halted near Dayr for a rest and the men lit fires and became busy preparing their meal. Buhayra watched the people of the caravan very carefully, and, again, amazing things caught his attention. Despite the fact that he never paid attention to caravans, this time he invited the people of the caravan to be his guests.
As they entered Dayr, he welcomed them and looked at the faces of his guests very carefully, as if looking for someone lost. Suddenly he cried, "Dear child! Come closer so I can see you... Hm,...It seems it is him...Come closer!"
The young lad had caught his attention. He held him, bent down, put his hands on his shoulders, and for a while looked at his face from close up.
He asked what his name was. He was told "Muhammad".
For a while he stood silently gazing at Muhammad (S.A.W.) then he sat down in front of him with great respect. He held his hands and asked him questions. He was very inquisitive and thorough; he spoke to Abu Talib and he asked the others questions too.
He had found his "lost one", and he looked very happy.
He looked at Abu Talib and said, "This child has a brilliant future and will attain a great position.
"This child is the very Prophet of whose coming the previous Prophets have given glad tidings.
"I have read his signs in the scriptures. He is the Last of God's Prophets. Soon he will receive his Prophetic mission and his religion will spread throughout the world. Know the worth of this child and make every effort to guard and protect him."
After resting, the caravan loaded up and departed. Buhayra had come out of Dayr and was watching Muhammad (S.A.W.) and shedding tears. After an hour, the caravan could no longer be seen, and Buhayra returned to his room, sat down alone, and buried himself in thought.