It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) ascended the pulpit, having tied a greasy band around his head. He (peace and blessings be upon him) praised and glorified Allah, then said: "People will keep increasing and the Ansar will keep decreasing, until they become among the people like salt in food. So whoever among you is put in charge of a matter by which some people are benefited and others harmed, let him accept good from those of them who do good, and overlook the faults of those of them who do wrong." The narrator said: This was the last sermon that the Messenger of Allah (peace and blessings be upon him) delivered before he passed away.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11634