Musannaf Ibn Abi Shayba 27:351

Husayn ibn Ali narrated to us, from Za'idah, from Asim ibn Abi al-Najud, from Zirr, from Abdullah, who said: When the righteous are mentioned, then come quickly to Umar. Indeed, his Islam was a victory, and his leadership was a conquest. By Allah, I do not know of anything on the earth except that it has felt the loss of Umar, even the thorny trees. By Allah, I truly think there is an angel between his eyes who directs him and guides him. And by Allah, if I knew that a dog loved Umar, I would love it.