Sunan an-Nasa'i 2643

It was narrated from Al-Fadl bin 'Abbas that:he was riding behind the Messenger of Allah and a man came and said: "O Messenger of Allah! My mother is an old woman and she cannot sit firmly in the saddle. If I tie her I fear that I may kill her." The Messenger of Allah said: "Don't you think that if your mother owed a debt you would pay it off?" He said: "Yes." Her said: "Then perform Hajj on behalf of your mother."(Shih)