Volume 4 · Book 52 · Hadith 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."
— Sahih Bukhari, Volume 4, Book 52: Fighting for the Cause of Allah (Jihaad), Hadith #101