Sahih Muslim
The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fadail Al-Sahabah)
Book Number: 031 / Hadith Number: 6103
Anas b. Malik reported Allah's Messenger (may peace be upon him) as saying: The Ansar are my family and my trusted friends. and the people would increase in number whereas they (the Ansar) would become less and less, so appreciate the deeds of those from amongst them who do good and overlook their failings.