For the purpose of making Islam attractive to black people, and to support that Islam is the natural religion of Africans – in contrast to Christianity as the religion of the slavers (cf. Christianity, Islam and Slavery) – some have claimed that Muhammad was a black (African) man. This has no factual basis.

Muhammad enslaved people, owned and sold slaves, including several black slaves.

Muhammad was neither black nor African: 

• white thigh, Sahih Bukhari 1.367, 
• white armpit, Sahih al-Bukhari 3564: Book 61, Hadith 74,
• white man, Sahih Bukhari 1.63, 2.122, 4.744

[….]

…there are some hadiths that link black skin and creation with judgment day:

Abu Darda’ reported God’s messenger as saying, “God created Adam when He created him and struck his right shoulder and brought forth his offspring white like small ants. And he struck his left shoulder and brought forth his offspring BLACK as though they were charcoal. Then He said to the party on his right said, ‘To paradise, and I do not care’, and He said to the party in his left shoulder ‘To hell, and I do not care‘.” — Ahmad transmitted it. (Mishkat Al Masabih, English translation with explanatory notes by Dr. James Robson [Sh. Muhammad Ahsraf Publishers, Booksellers & Exporters, Lahore-Pakistan, Reprint 1990], Volume I, Chapter IV, Book I.- Faith, pp. 31-32)

Narrated AbudDarda’
Allah’s Messenger (peace be upon him) said: Allah created Adam when He had to create him and He struck his right shoulder and there emitted from it white offspring as if they were white ants. He struck his left shoulder and there emitted from it THE BLACK OFFSPRINGS as if they were charcoal. He then said (to those who had been emitted) from the right (shoulder): For Paradise and I do not mind. Then He said to those (who had been emitted) from his left shoulder: They are for Hell and I do not mind. — Transmitted by Ahmad. (Al-Tirmidhi Hadith, Number 38- ALIM CD ROM Version)

For these traditions, it is much harder to resist the impression of racist overtones. They do not speak about people being whitened or blackened at the time of judgment, but link their original skin color with their eternal destiny, i.e. Allah decreed that blacks will enter hell in contrast to whites.

In fact, other narrations even command that any person claiming that Muhammad was black be put to death!

Ahmad ibn Abi Sulayman, the companion of Sahnun, said, “Anyone who says that the Prophet was black SHOULD BE KILLED.” (Muhammad Messenger of Allah (Ash-Shifa of Qadi ‘Iyad), Qadi ‘Iyad Musa al-Yahsubi, translated by Aisha Abdarrahman Bewley [Madinah Press, Inverness, Scotland, U.K. 1991; third reprint, paperback], p. 375; capital emphasis ours)

Ahmad ibn Abi Sulayman, Sahnun’s companion, said that whoever says that the Prophet was black IS KILLED. The Prophet was not black. (Ibid., p. 387; capital emphasis ours)

The Nation of Islam teaches that white people are devils. Their members might want to ponder this statement by Muhammad:

… The apostle said, “Whoever wants to see Satan let him take a look at Nabtal b. al-Harith!” He was a sturdy black man with long flowing hair, inflamed eyes, and dark ruddy cheeks. He used to come and talk to the apostle and listen to him and then carry what he had said to the hypocrites. It was he who said: “Muhammad is all ears: if anyone tells him anything he believes it.” God sent down concerning him: “And of them are those who annoy the prophet and say he is all ears, Say: Good ears for you. He believes in God and trusts the believers and is a mercy for those of you who believe; and those who annoy the apostle of God for them there is a painful punishment.” (Sura 9:61) (Ibn Ishaq, Sirat Rasulallah, translated as, The Life of Muhammad by A. Guillaume, page 243)