Musannaf Ibn Abi Shayba 3:1911

Ghundar narrated to us, from Shu'bah, from Sa'd ibn Ibrahim, from Tha'labah ibn 'Abd Allah ibn al-Asghar (al-Su'ayr), that he prayed with 'Umar ibn al-Khattab, and he (Umar) recited Surah al-Hajj, and he performed two prostrations in it.