Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
nasai-kubra:321Isḥāq b. Ibrāhīm > al-Naḍr b. Shumayl > Ḥammād b. Salamah > al-Azraq b. Qays > Yaḥyá b. Yaʿmur > Abū Hurayrah

"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." (Using translation from Nasāʾī 467)  

الكبرى للنسائي:٣٢١أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ حَدَّثَنَا النَّضْرُ بْنُ شُمَيْلٍ قَالَ أَخْبَرَنَا حَمَّادُ بْنُ سَلَمَةَ عَنِ الْأَزْرَقِ بْنِ قَيْسٍ عَنْ يَحْيَى بْنِ يَعْمُرَ عَنْ أَبِي هُرَيْرَةَ

عَنْ رَسُولِ اللهِ ﷺ قَالَ إِنَّ أَوَّلَ مَا يُحَاسَبُ بِهِ الْعَبْدُ صَلَاتُهُ فَإِنْ كَانَ أَكْمَلَهَا وَإِلَّا قَالَ اللهُ انْظُرُوا أَلِعَبْدِي مِنْ تَطَوُّعٍ فَإِنْ وُجِدَ لَهُ تَطَوُّعٌ قَالَ أَكْمِلُوا بِهِ الْفَرِيضَةَ  


See similar narrations below:

Collected by Nasāʾī
nasai:467Isḥāq b. Ibrāhīm > al-Naḍr b. Shumayl > Ḥammād b. Salamah > al-Azraq b. Qays > Yaḥyá b. Yaʿmar > Abū Hurayrah

"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."  

النسائي:٤٦٧أَخْبَرَنَا 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 ﷺ قَالَ أَوَّلُ مَا يُحَاسَبُ بِهِ الْعَبْدُ صَلاَتُهُ فَإِنْ كَانَ أَكْمَلَهَا وَإِلاَّ قَالَ اللَّهُ ﷻ انْظُرُوا لِعَبْدِي مِنْ تَطَوُّعٍ فَإِنْ وُجِدَ لَهُ تَطَوُّعٌ قَالَ أَكْمِلُوا بِهِ الْفَرِيضَةَ