صحيح مسلم

It has been narrated (through a still difterent chain of transmitters) by Anas that the Companions of Muhammad (ﷺ) were chanting on the day of the Battle of the Ditch: We are those who have sworn allegiance to Muhammad (And made a covenant with him) to follow Islam as long as we live. Hammad is not sure whether Anas said:" Ala'l-Islam" or," Ala'l-Jihad". And the Prophet (ﷺ) was chanting: O God, the real good is the good of the Hereafter, So forgive Thou the Ansar and the Muhajirs.