It is narrated from Hazrat Aisha (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said: "Bilal gives the call to prayer (Adhan) when there is still a part of the night remaining, so after his Adhan you may eat and drink, until Ibn Umm Maktum gives the Adhan." She says: "To my knowledge, the time between their Adhans was only as much as it would take for someone to go down and another to climb up."