Sayyiduna Abu Mahdhurah (may Allah be pleased with him) says: In the time of the Noble Prophet (peace and blessings be upon him), I used to give the call to prayer (adhan) for the morning prayer. When I would say "Hayya 'ala al-falah," I would say "As-salatu khayrun min an-nawm, as-salatu khayrun min an-nawm." This refers to the first adhan.