Musnad Ahmad 30:2906

Muhammad ibn Ja‘far and Bahz—the meaning is the same—said: Shu‘bah narrated to us, from al-Hakam. Bahz said in his narration: Al-Hakam informed me, from Muhammad ibn ‘Ali, that a man said to Abu Hurayrah: "Indeed, ‘Ali recites Surah al-Jumu‘ah and 'Idha Ja’aka al-Munafiqun' on the day of Jumu‘ah." Abu Hurayrah said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to recite them both."