Regarding The Statement Of The Prophet (saws) "Every Prayer That One Does Not Perfect It Will Be Made Complete By The Voluntary Ones"

Narrated AbuHurayrah: Anas ibn Hakim ad-Dabbi said that he feared Ziyad or Ibn Ziyad; so he came to Medina and met AbuHurayrah. He attributed his lineage to me and I became a member of his lineage. AbuHurayrah said (to me): O youth, should I not narrate a tradition to you? I said: Why not, may Allah have mercy on you? (Yunus (a narrator) said: I think he narrated it (the tradition) from the Prophet (ﷺ):) The first thing about which the people will be called to account out of their actions on the Day of Judgment is prayer. Our Lord, the Exalted, will say to the angels - though He knows better: Look into the prayer of My servant and see whether he has offered it perfectly or imperfectly. If it is perfect, that will be recorded perfect. If it is defective, He will say: See there are some optional prayers offered by My servant. If there are optional prayer to his credit, He will say: Compensate the obligatory prayer by the optional prayer for My servant. Then all the actions will be considered similarly.