Musnad Ahmad 1153:25

Muhammad ibn Abd al-Rahman al-Tafawi narrated to us, he said: Hisham ibn Urwah narrated to us, from his father, from Aisha, who said: "The Messenger of Allah, may Allah bless him and grant him peace, never struck a servant of his at all, nor a woman of his at all, nor did he strike with his hand, except when striving in the way of Allah. And he was never wronged in anything and then took revenge from the one who did it, unless the sanctities of Allah the Almighty were violated, in which case he would take revenge for the sake of Allah the Almighty. And he was never presented with two matters, one of which was easier than the other, but he would take the easier of the two, unless it was a sin. If it were a sin, he would be the furthest of people from it."