It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him): the Prophet (peace and blessings be upon him) said: "The people of the early part of this Ummah are the best, and the people of its last part will be the worst; they will be at variance with one another and divided from one another. Whoever believes in Allah Almighty and the Last Day, when death comes to him, his state should be that he treats people the way he would like to be treated."
Al-Tabarani recorded it; its chain contains a narrator, al-Mufaddal bin Ma'ruf, whom I do not know; its remaining narrators are thiqat (trustworthy).