Musnad Ahmad 30:2297

Qutaybah narrated to us, Hatim ibn Isma'il narrated to us, from Salih ibn Muhammad ibn Za'idah, from Abu Salamah ibn 'Abd al-Rahman, from 'Aishah, that she said: The Messenger of Allah, may Allah bless him and grant him peace, would not raise his head toward the sky except that he said: "O Turner of hearts, keep my heart firm upon Your obedience."