Sunan an-Nasa'i 467
سنن النسائي#467Sahihأَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا النَّضْرُ بْنُ شُمَيْلٍ، قَالَ أَنْبَأَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنِ الأَزْرَقِ بْنِ قَيْسٍ، عَنْ يَحْيَى بْنِ يَعْمَرَ، عَنْ أَبِي هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ " أَوَّلُ مَا يُحَاسَبُ بِهِ الْعَبْدُ صَلاَتُهُ فَإِنْ كَانَ أَكْمَلَهَا وَإِلاَّ قَالَ اللَّهُ عَزَّ وَجَلَّ انْظُرُوا لِعَبْدِي مِنْ تَطَوُّعٍ فَإِنْ وُجِدَ لَهُ تَطَوُّعٌ قَالَ أَكْمِلُوا بِهِ الْفَرِيضَةَ " .
It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:"The first thing for which a person will be brought to account will be his Salah. If it is complete (all well and good), otherwise Allah will say: 'Look and see if My slave did any voluntary prayer.' If he is found to have done voluntary prayers, his obligatory prayers will be completed therewith
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 5:20