Musnad Ahmad 1153:619

Bahz narrated to us, he said: Hammam narrated to us, he said: Qatadah narrated to us, from Zurarah ibn Awfa, that Sa’d ibn Hisham narrated to him, he said: I said: "O Mother of the Believers, tell me about the character of the Messenger of Allah, may Allah bless him and grant him peace." She said: "Do you not read the Quran?" He said: I said: "Yes." Then he mentioned the hadith. She said: "The Messenger of Allah, may Allah bless him and grant him peace, when he performed a prayer, he would persist in it. And if he missed the night prayer—due to his eyes overcoming him with sleep, or pain—he would pray twelve rak'ahs during the day." She said: "The Messenger of Allah, may Allah bless him and grant him peace, did not spend a night standing in prayer until the morning, nor did he recite the entire Quran in a single night, nor did he fast a full month other than Ramadan until he died."