Sahih Muslim: Hadith 6435

You would soon conquer Egypt and that is a land which is known (as the land of al-qirat). So when you conquer it, treat its inhabitants well. For there lies upon you the responsibility because of blood-tie or relationship of marriage (with them). And when you see two persons falling into dispute amongst themselves for the space of a brick, than get out of that. He (Abu Dharr) said: I saw Abd al-Rahman b. Shurahbil b. Hasana and his brother Rabi'a disputing with one another for the space of a brick. So I left that (land).