Musnad Ahmad 30:2809

'Abd al-Rahman narrated to us, from Sufyan, from Ayyub ibn Musa, from 'Ata' ibn Mina', from Abu Hurayrah, who said: "We prostrated with the Messenger of Allah, may Allah bless him and grant him peace, during [the recitation of] 'When the sky has split [Idha al-sama'u inshaqqat]' and 'Recite in the name of your Lord [Iqra' bismi rabbika].'"