Musnad Ahmad 32:1824

'Abdullah ibn Bakr narrated to us, Humaid narrated to us, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A people will come to you who are more tender-hearted than you." When they drew near to Medina, they began to chant in *rajaz* meter: Tomorrow we shall meet the beloved, Muhammad and his party. Then the Ash'aris arrived, among them Abu Musa al-Ash'ari.