Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 101
Narrated Malik bin Al-Huwairith:
On my departure from the Prophet he said to me and to a friend of mine, "You two, pronounce the Adhan and the Iqama for the prayer and let the elder of you lead the prayer."