Musnad Ahmad 1153:391

Hassan narrated to us, saying: Ibn Lahi'ah narrated to us, Abu al-Aswad narrated to us, from al-Qasim ibn Muhammad, from Aisha, who said: "Nothing of the world ever amazed the Messenger of Allah, peace and blessings of Allah be upon him, nor did anyone ever amaze him at all, except for a person of piety."