It is narrated from Sayyidah Aisha (may Allah be pleased with her) that the Noble Prophet (peace and blessings be upon him) had two muezzins: Bilal and the son of Umm Maktum. So the Messenger of Allah (peace and blessings be upon him) said: "Bilal gives the call to prayer during the night, so keep eating and drinking until you hear the call to prayer of Ibn Umm Maktum." Qasim said: There was such an interval between their calls to prayer that one would descend and the other would ascend (for the call to prayer).