Musnad Ahmad

Anas bin Hakim, may Allah have mercy on him, says that when he faced danger during the time of Ziyad or Ibn Ziyad, he came to Madinah Munawwarah. He met Hazrat Abu Hurairah, may Allah be pleased with him, who asked me about my name and lineage. I told him, and he said, "O young man, shall I not narrate to you a hadith from which Allah may benefit you?" I said, "Why not, may Allah's mercy be upon you." He said: "On the Day of Resurrection, the first thing for which a servant will be called to account will be the obligatory prayer. The Lord will say to His angels—though He knows best—'Look at My servant's prayer, is it complete or deficient?' If it is complete, it will be recorded as complete. If it is incomplete, Allah the Exalted will say, 'See if My servant has any voluntary prayers.' If he has voluntary prayers, Allah will say, 'Complete My servant's obligatory prayers with his voluntary prayers.' After that, the same will be done with the rest of the obligatory deeds."