Musnad Ahmad 5:125

Aswad narrated to us, Israel narrated to us, from Abu Ishaq, from al-Harith, from Ali, who said: "The Messenger of Allah, may Allah bless him and grant him peace, recited [the Quran] after he had passed wind, before he touched water." And perhaps Israel said: From a man, from Ali, from the Prophet, may Allah bless him and grant him peace.