Musnad Ahmad 30:2731

Hajjaj narrated to us, he said: Ibn Abi Dhi'b and Abu al-Nadr narrated to us, from Ibn Abi Dhi'b, from 'Abd al-'Aziz ibn 'Ayyash, from 'Umar ibn 'Abd al-'Aziz, from Abu Salamah, from Abu Hurairah, from the Prophet, peace and blessings of Allah be upon him: "That he prostrated during [the recitation of] 'When the sky has split [Idha al-sama'u inshaqqat]'."