This is Allah teaching His Messenger how to receive the revelation from the angel. For verily, he (the Prophet ) was rushing in his attempts to grasp the revelation and he would be reciting the revelation with the angel while he was reciting it. Therefore, Allah commanded him that when the angel brings some revelation to him he should just listen. Allah would make sure to collect it in his chest, and He would make it easy for him to recite it in the same way that it was revealed to him. Allah would explain it, interpret it and clarify it for him. So the first phase was gathering it in his chest, the second phase was recitation and the third phase was its explanation and clarification of its meaning. Thus, 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.