Call to Prayers (Adhaan)

Bukhari :: Book 1 :: Volume 11 :: Hadith 606

Narrated 'Aun bin Abi Juhaifa:

My father said, "I saw Allah's Apostle at a place called Al-Abtah. Bilal came and informed him about the prayer and then came out with an Anza and planted it in front of Allah's Apostle at Al-Abtah and pronounced the Iqama."