Musannaf Ibn Abi Shayba 3:11

Abu Bakr narrated to us, he said: Hushaym narrated to us, from Mughirah, from Ibrahim, who said: When Umar would begin the prayer, he would say the takbir. He then mentioned the like of the hadith of Husayn, and added in it: "He would recite them aloud." Ibrahim said: "He does not recite them aloud."