Sahih Muslim Book 4, Hadith Number 1256.

Chapter : Desirability of going to prayer with dignity and tranquillity and forbiddance of going to it in hot haste.

Abu Salama son of Abd al-Rahman b. Auf reported Abu Huraira as saying: Iqama was pronounced and we stood up and made rows straight till he (the Holy Prophet) stood at his place of worship (the place ahead of the rows where he stood to lead the prayer) before takbir tahrima. He reminded to (himself something) and went back saying that we should stand at our places and not leave them. We waited, till he came back to us and he had taken a bath and water trickled out of his head and then led us in prayer.