Musnad Abu Ya'la al-Mawsili 129:128

Zuhayr narrated to us, Yazid narrated to us, Humayd narrated to us, from Anas, that the Messenger of Allah (may Allah bless him and grant him peace) said: "A people will arrive who are softer in heart than you." Then the Ash'ariyyun arrived, among them Abu Musa. They began to chant in *rajaz* meter, saying: "Tomorrow we shall meet the beloved ones, Muhammad and his party."