Sahih Bukhari Volume 1, Book 11, Hadith Number 613

Narated By Abu Huraira : Once iqama was pronounced and the people had straightened the rows, Allah’s Apostle went forward (to lead the prayer) but he was Junub, so he said, “Remain in your places.” And he went out, took a bath and returned with water trickling from his head. Then he led the prayer.