Musannaf Ibn Abi Shayba 3:6406

Abu Bakr narrated to us, he said: Muhammad ibn Bishr al-‘Abdi narrated to us, he said: ‘Abdullah ibn al-Walid narrated to us, he said: ‘Umar ibn Muhammad ibn Hatib narrated to us, he said: A great man from among the great men of the non-Arabs (Ajam) came to ‘Umar and asked about ‘Umar. It was said to him that he had gone out of the city, so he went out to him. He said: He met him while he was approaching. The Dihqan (Persian chieftain) leaned down and prostrated, or intended to prostrate, to ‘Abdullah—I am in doubt. He said: So ‘Umar said, "Raise your head to the One, the Subduer (al-Wahid al-Qahhar)."