Musnad Ahmad 572:22

Aswad ibn Amir narrated to us, Hureym narrated to us, from Layth, from Shahr ibn Hawshab, from Uthman ibn Abi al-As, who said: I was sitting with the Messenger of Allah, peace and blessings of Allah be upon him, when he fixed his gaze upward, then lowered it until it almost touched the ground. He said: "Then he fixed his gaze upward and said: 'Gabriel came to me and commanded me to place this verse in this position of this surah: {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].'"