Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 482
Narated By AbuSahlah as-Sa'ib ibn Khallad : A man led the people in prayer. He spat towards qiblah while the Apostle of Allah (pbuh) was looking at him. The Apostle of Allah said to the people when he finished his prayer: He should not lead you in prayer (henceforth).
Thenceforth he intended to lead them in prayer, but they forbade him and informed him of the prohibition of the Apostle of Allah (pbuh). He mentioned it to the Apostle of Allah (pbuh) who said to him: Yes.
The narrator said: I think he (the Prophet) said: You did harm to Allah and His Apostle.