Musnad Ahmad 25:1060

Abu al-Nadr narrated to us, he said: Abd al-Hamid narrated to us, Shahr narrated to us, Abdullah ibn Abbas narrated to us, he said: While the Messenger of Allah (peace and blessings of Allah be upon him) was sitting in the courtyard of his house in Makkah, Uthman ibn Maz'un passed by him. He smiled at the Messenger of Allah (peace and blessings of Allah be upon him), and the Messenger of Allah (peace and blessings of Allah be upon him) said to him: "Will you not sit?" He said: "Yes." He said: So the Messenger of Allah (peace and blessings of Allah be upon him) sat facing him. While he was speaking to him, the Messenger of Allah (peace and blessings of Allah be upon him) fixed his gaze toward the sky. He looked at the sky for a while, then he began to lower his gaze until he placed it to his right on the ground. The Messenger of Allah (peace and blessings of Allah be upon him) turned away from his companion, Uthman, toward where he had placed his gaze, and he began to nod his head as if he were trying to understand what was being said to him, while Ibn Maz'un was watching. When he had finished his need and understood what was being said to him, the gaze of the Messenger of Allah (peace and blessings of Allah be upon him) fixed toward the sky just as it had fixed the first time, and he followed it with his gaze until it disappeared into the sky. Then he turned back to Uthman in his original sitting position. He said: "O Muhammad, in what I have been sitting with you and coming to you, I have never seen you do as you did this morning." He said: "And what did you see me do?" He said: "I saw you fix your gaze toward the sky, then you placed it where you placed it to your right, so you turned toward it and left me, and you began to nod your head as if you were trying to understand something being said to you." He said: "And did you notice that?" Uthman said: "Yes." The Messenger of Allah (peace and blessings of Allah be upon him) said: "The Messenger of Allah came to me just now, while you were sitting." He said: "The Messenger of Allah?" He said: "Yes." He said: "And what did he say to you?" He said: "{Indeed, Allah orders justice and good conduct and giving to relatives and forbids immorality and bad conduct and oppression. He admonishes you that perhaps you will be reminded} [An-Nahl: 90]." Uthman said: "That was when faith settled in my heart, and I loved Muhammad."