Musannaf Ibn Abi Shayba 3:77

Yahya ibn Adam narrated to us, from Hasan ibn Ayyash, from Abd al-Malik ibn Abjar, from al-Zubayr ibn Adi, from Ibrahim, from al-Aswad, who said: I prayed with Umar, and he did not raise his hands in any part of his prayer except when he commenced the prayer. Abd al-Malik said: And I saw al-Sha'bi, Ibrahim, and Abu Ishaq not raising their hands except when they commenced the prayer.