It is narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The best of the tribes of the Ansar are the households of Banu al-Najjar, then Banu Abd al-Ashhal, then Banu al-Harith, then Banu Sa'idah; and in all of the Ansar there is good."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5715