The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fada'il Al-Sahabah)
Muslim :: Book 31 : Hadith 6170
Usair b. Jabir reported that a delegation from Kufa came to 'Umar and there was a person amongst them who jeered at Uwais. Thereupon Umar said: Is there amongst us one from Qaran? That person came and Umar said: Verily Allah's Messenger (may peace be upon him) has said: There would come to you a person from Yemen who would be called Uwais and he would leave none in Yemen (behind him) except his mother, and he would have the whiteness (due to leprosy) and he supplicated Allah and it was cured except for the size of a dinar or dirham. He who amongst you meets him should ask him to supplicate for forgiveness (from Allah) for you.