Abu `Amir al-Ash`ari reported God's messenger as saying, "Asad and the members of Ash'ar[*] are good. They do not fly when fighting and are not treacherous. They pertain to me and I to them."
*Mirqat, 5:511, suggests the reading Asd and says that both Ash'aruna and Ash'ariyuna are used. It says the former here refers to Azd Shanu'a. But there was a branch of Quraish called Asad.
Tirmidhi transmitted it, saying this is a gharib tradition.