Call to Prayers (Adhaan)

Bukhari :: Book 1 :: Volume 11 :: Hadith 693

Narrated Ibn 'Abbas:

I prayed with the Prophet one night and stood on his left side. Allah's Apostle caught hold of my head from behind and drew me to his right and then offered the prayer and slept. Later the Mu'adh-dhin came and the Prophet stood up for prayer without performing ablution.