Musnad Ahmad 1153:2243

Ishaq narrated to us, Malik informed us, from al-Zuhri, from Urwah, from Aisha, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) was never given a choice between two matters except that he chose the easier of the two, as long as it was not a sin. If it were a sin, he would be the furthest of people from it. The Messenger of Allah (peace and blessings of Allah be upon him) never took revenge for his own sake, unless the sanctities of Allah were violated, in which case he would take revenge for the sake of Allah, the Almighty and Majestic."