Musannaf Ibn Abi Shayba 24:133

Ubayd Allah ibn Musa narrated to us, Shayban narrated to us, from al-A’mash, from Abu al-Duha, who said: Someone who heard Umar say when he saw al-Mughira ibn Shu’ba narrated to me: "Woe to you, O Mughira! By Allah, I have never seen you except that I feared [that Allah might punish me because of you]."