Call to Prayers (Adhaan)

Bukhari :: Book 1 :: Volume 11 :: Hadith 601

Narrated Malik bin Huwairth:

I came to the Prophet with some men from my tribe and stayed with him for twenty nights. He was kind and merciful to us. When he realized our longing for our families, he said to us, "Go back and stay with your families and teach them the religion, and offer the prayer and one of you should pronounce the Adhan for the prayer when its time is due and the oldest one amongst you should lead the prayer."