Sahih Bukhari
Call to Prayers (Adhaan)
Volume: 001 / Book Number: 011 / Hadith Number: 661
Narrated Ibn 'Umar:
When the earliest emigrants came to Al-'Usba a place in Quba', before the arrival of the Prophet- Salim, the slave of Abu Hudhaifa, who knew the Qur'an more than the others used to lead them in prayer.