In the Name of Allah, the Most Gracious, the Most Merciful.
The Oath about the Final Return on the Day of Resurrection and the Refutation against the Plots
It has been mentioned previously on more than one occasion that if the thing that is being sworn about is something that is being negated, then it is permissible to use the word "La" (Nay) before the oath to emphasize the negation. Here, what is being sworn about is the affirmation of the final abode and the refutation against the claim of the ignorant that the resurrection of bodies will not occur. This is why Allah says,
بَلِ الْاِنْسَانُ عَلٰي نَفْسِهٖ بَصِيْرَةٌ وَّلَوْ اَلْقٰى مَعَاذِيْرَهٗ (Rather, man will be a witness against himself, even though he may offer his excuses....75:14-15). One meaning of the words bash and basirah is 'to see'. Another meaning of basirah is 'evidence', as for instance in:
قَدْ جَاۗءَكُمْ بَصَاۗىِٕرُ مِنْ رَّبِّكُمْ
'...There have come to you evidences 1 from your Lord_[ 6:104] '
In this verse the word basa'ir is the plural of basirah and it means 'evidence, proof, argument or insight'. The word ma` adhir is the plural of mi` dhar meaning, 'excuse'. The verse purports to say that for purposes of following the procedures of fairness and justice, man will be shown each
Man has the innate capacity to distinguish between good and evil. By his very nature he wants anyone indulging in evil to be punished and anyone doing righteous deeds to be rewarded. It is this consciousness which is called in the Quran the self-reproaching soul or an-nafs al-lawwamah. This faculty bears testimony at the psychological level to the reality of the world of the Hereafter. If, in spite of this inner testimony, an individual does not fulfill its demands, it means that he negates what he has already accepted.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.