Musannaf Ibn Abi Shayba 3:1187

Abu Mu'awiyah narrated to us, from al-A'mash, from Ibrahim al-Taymi, from Husayn ibn Sabrah, who said: I prayed behind Umar, and he recited in the first rak'ah Surah Yusuf, then he recited in the second [rak'ah] al-Najm. Then he stood up and recited "Idha zulzilat," then he bowed.