Sahih Muslim Book 1, Hadith Number 431.

Chapter : This Ummah (Ummah of Islam) would constitute half of the inhabitants of Paradise. The same hadith has been narrated from A’mash on the authority of the same chain of transmitters with the exception of these words: You would be no more among men (on the Day of Resurrection) but like a white hair on (the body of) a black ox, or like a black hair on (the body of) a white ox, and he made no mention of: a strip on the foreleg of an ass.