Hazrat Buraidah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: I heard the sound of footsteps ahead of me, so I asked: Who is this? The angels said: It is Bilal (may Allah be pleased with him). Then the Prophet (peace and blessings be upon him) informed Hazrat Bilal (may Allah be pleased with him) of this and asked: By which deed have you preceded me? He (may Allah be pleased with him) replied: O Messenger of Allah (peace and blessings be upon him)! Whenever I became impure, I performed ablution, and whenever I performed ablution, I thought that surely Allah has a right upon me for two units of prayer, so I performed them. The Prophet (peace and blessings be upon him) said: It is because of this.