Musnad Abu Ya'la al-Mawsili 155:207

Abu Hisham al-Rifa'i narrated to us, Abu 'Amir narrated to us, Qurrah narrated to us, from Ibn Sirin, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him): That he prostrated in "When the sky has split [Idha al-sama'u inshaqqat]" (Surah al-Inshiqaq), and Abu Bakr and 'Umar and he who is better than both of them [prostrated]. And he prostrated in "Recite in the name of your Lord [Iqra' bismi Rabbika]" (Surah al-'Alaq), and Abu Bakr and 'Umar and he who is better than both of them [prostrated].