He called for the rights of the oppressed and the poor and stood by them, which drew the anger and wrath of the strong.
In order to persuade him to abandon his belief and duty of prophethood, all sorts of schemes like bribery, torture and banishment were used.
Despite all these abuses, none of his followers deserted Islam. In 622 AD, Muhammad received a command from Allah to migrate to Medina, a city north of Mecca.
This event was so momentous that the Islamic calendar begins with this migration (Hijrah). In Medina, Muslims became a more cohesive society.
More people from every religion, tribe and race embraced Islam. People from all parts were affected by the outstanding character and grace of the Prophet.
Eight years after the Hijrah, the Prophet Muhammad returned to Mecca with an army of 10,000 men under the strict order that no blood was to be spilt, no revenge was to be taken.
He respectfully rode into Mecca on the back of his camel bowing so much so that his head nearly rested on the camel's neck.
Upon entering the city, he told its Meccans: "I say to you what the Prophet Joseph (Yusuf) said to his brothers, 'This day, no reproach be cast on you. May Allah forgive you. You are free.'"
The following year in the pilgrimage (hajj) season, he gave his farewell sermon in which he said:
"We have put the ways of ignorance behind us now. We must drop all ties with usury. Justice needs to prevail, and no one should ever be oppressed. Everyone is equal regardless of black or white, rich or poor, Arab or non-Arab. The thing that distinguishes us from one another is piety; there shall be no more paganism..."
In the meanwhile, he received the following verse, which is called "ayah" in the Qur'an, meaning "sign" in Arabic: "This day have I perfected for you your religion and completed My favor on you and chosen for you Islam as religion…" (Ma'idah, 5/3)
It is believed to be one of the last ayahs the Prophet received.