Sayyiduna Anas bin Malik (may Allah be pleased with him) said: Once we were sitting with the Prophet (peace and blessings be upon him) in the mosque. Suddenly a man came on a camel; he made his camel kneel in the mosque, then tied it. Then he said to the people: Which of you is Muhammad (peace and blessings be upon him)? He (peace and blessings be upon him) was sitting among us, reclining. We said to him: This fair-complexioned man who is reclining. Then the man said: O son of Abd al-Muttalib! He (peace and blessings be upon him) said: "I have answered you." The man said: O Muhammad (peace and blessings be upon him)! I am going to ask you some questions; if anything in my questioning seems harsh to you, do not take it badly. He (peace and blessings be upon him) said: "Ask whatever you want to ask." He said: I adjure you by your Lord and the Lord of those before you: has Allah sent you as a Messenger to all people? He (peace and blessings be upon him) said: "Yes, indeed." The man then said: I adjure you by Allah: has Allah commanded you that we pray five prayers in a day and night? He said: "Yes, indeed." The man then said: I adjure you by Allah and ask: has Allah commanded you that we fast for one month in the year? He (peace and blessings be upon him) said: "Yes." The man then said: I adjure you by Allah and ask: has Allah commanded you to collect sadaqah from our wealthy people and distribute it among the poor? He (peace and blessings be upon him) said: "Yes." Finally he said: I have believed in what you have brought, and I will deliver this message to the people of my tribe; I am Dimam bin Tha'labah, the brother of Banu Sa'd bin Bakr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13137