Musnad Ahmad 937:230

Wahb ibn Jarir narrated to us, my father narrated to us, he said: I heard Harmalah narrating from Abd al-Rahman ibn Shamasa, from Abu Basrah, from Abu Dharr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "You will surely conquer Egypt, and it is a land in which the *qirat* is mentioned. So when you conquer it, treat its people well, for they have a covenant and a kinship," or he said: "a covenant and an affinity." "And if you see two men disputing therein over the space of a brick, then leave it." He [Abu Dharr] said: "Then I saw Abd al-Rahman ibn Sharhabil ibn Hasana and his brother Rabi'ah disputing over the space of a brick, so I left it."