Musnad Abu Ya'la al-Mawsili 117:59

Muhammad ibn al-Khattab narrated to us, Abd al-Malik ibn Ibrahim narrated to us, Sulayman ibn al-Mughirah narrated to us, Thabit al-Bunani narrated from Anas, who said: We used to fear asking the Messenger of Allah (may Allah bless him and grant him peace) about anything, and it used to please us when a man from the people of the desert would come to him and ask him while we were listening. A man from them came to him and said: "O Muhammad, your messenger came to us and claimed that you claim that Allah sent you." He said: "He spoke the truth." He said: "Then who created the heaven?" He said: "Allah." He said: "Then who created the earth?" He said: "Allah." He said: "Then who set up these mountains?" He said: "Allah." He said: "Then who placed these springs within them?" He said: "Allah." He said: "Then by the One who created the heaven and the earth, and set up the mountains, and placed these springs within them, did Allah send you?" He said: "Yes." He said: "Your messenger claimed that we have five prayers in our day and our night." He said: "He spoke the truth." He said: "Then by the One who sent you, did Allah command you with this?" He said: "Yes." He said: "Your messenger claimed that we have charity upon our wealth." He said: "He spoke the truth." He said: "Then by the One who sent you, did Allah command you with this?" He said: "Yes." He said: "Your messenger claimed that we have the fasting of a month in our year." He said: "He spoke the truth." He said: "Then by the One who sent you, did Allah command you with this?" He said: "Yes." He said: "Your messenger claimed that we have the pilgrimage to the House for whoever is able to find a way to it." He said: "He spoke the truth." He said: "Then by the One who sent you, did Allah command you with this?" He said: "Yes." He said: "By the One who sent you with the truth, I will not add to them, nor will I decrease anything from them." He said: "Then when he turned to leave, he said: 'If he is truthful, he shall surely enter Paradise.'"