Musnad Ahmad 32:763

Abu Mu'awiyah narrated to us, Yahya bin Sa'id narrated to us, from Anas bin Malik, who said: The Messenger of Allah (peace and blessings of Allah be upon him) invited us to write for us a land grant in Bahrain. He said: So we said: "No, unless you write for our brothers from the Emigrants (Muhajirun) the like of it." He said: "You will encounter after me selfishness (favoritism), so be patient until you meet me." They said: "We will be patient."