Musnad Ahmad 1153:280

Ibn Numayr narrated to us, from Hisham, from his father, from Aisha: "That the Messenger of Allah, peace and blessings of Allah be upon him, when he would command them to do deeds they were capable of, they would say: 'O Messenger of Allah, we are not like you; Allah, the Mighty and Majestic, has forgiven you your past sins and your future ones.' She said: 'Then he would become angry until the anger was recognizable on his face.'"