Sayyiduna Malik bin al-Huwayrith (may Allah be pleased with him) said: We came to the Messenger of Allah (peace and blessings be upon him) while we were young men, and we stayed with him about twenty nights or days. Then the Messenger of Allah (peace and blessings be upon him) said to us: "When you return to your families - or he said: to your lands - teach them (the religion)." The narrator said: And the Messenger of Allah (peace and blessings be upon him) was very compassionate. "Command them to pray such-and-such a prayer at such-and-such a time, and such-and-such a prayer at such-and-such a time; and when the time of prayer comes, let one of you give the adhan, then let the eldest of you lead you in prayer." This is the wording of Arim's narration.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16684