From Sahih Bukhari (Hadith 640):
Narrated Abu Huraira:Once Iqama was pronounced and the people had straightened the rows, Allah's Messenger (ﷺ) 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
Reference: Bukhari 640