Musannaf Ibn Abi Shayba 27:597

Waki' narrated to us, he said: Al-A'mash narrated to us, from Malik ibn al-Harith, from Abu Khalid, who said: I arrived as a delegate to Umar, and he favored the people of al-Sham over us in the stipend. So we spoke to him about it. He said: "O people of Kufa, are you distressed that I favored the people of al-Sham over you in the stipend due to the distance of their journey? I have indeed preferred you with the son of Umm 'Abd."