From Sahih Muslim (Hadith 6421):
Abu Usaid reported Allah's Messenger (ﷺ) as saying:The worthiest clans of the Ansar are Banu Najjar, thereafter Banu al-Ashhal; thereafter Banu Harith b. Banu Khazraj; thereafter Banu Sa'idah and there is goodness in all clans of the Ansar. Sa'd said: I see that he (the Holy Prophet) has placed others above us. It was said to (him): He has placed you above many others
Reference: Muslim 6421