ثُمَّ ءَاتَيْنَا مُوسَى ٱلْكِتَٰبَ تَمَامًا عَلَى ٱلَّذِىٓ أَحْسَنَ وَتَفْصِيلًا لِّكُلِّ شَىْءٍ … أَن تَقُولُوٓا۟ إِنَّمَآ أُنزِلَ ٱلْكِتَٰبُ عَلَىٰ طَآئِفَتَيْنِ مِن قَبْلِنَا وَإِن كُنَّا عَن دِرَاسَتِهِمْ لَغَٰفِلِينَ
"Then We gave Moses (Mūsā) the Book… lest you should say: 'The Book was sent down only to two communities before us, and we were unaware of their study of it.'"
I record this as an observation: throughout the sūra the words of the other side are transmitted directly (6/29, 6/109, 6/148) — and here a saying is transmitted that has not yet been said but could be. That is, the excuse is met before it is born.
And a second excuse is counted as well (157): aw taqūlū law annā unzila ʿalayna'l-kitābu la-kunnā ahdā minhum — "had the Book been sent down to us, we would have been better guided than they." The same claim was treated at Fāṭir 35/42; I rely on that treatment.
هَلْ يَنظُرُونَ إِلَّآ أَن تَأْتِيَهُمُ ٱلْمَلَٰٓئِكَةُ أَوْ يَأْتِىَ رَبُّكَ أَوْ يَأْتِىَ بَعْضُ ءَايَٰتِ رَبِّكَ يَوْمَ يَأْتِى بَعْضُ ءَايَٰتِ رَبِّكَ لَا يَنفَعُ نَفْسًا إِيمَٰنُهَا لَمْ تَكُنْ ءَامَنَتْ مِن قَبْلُ (158)
The non-acceptance of faith that comes at the last moment: treated at al-Zumar 39/54-59, Ghāfir (al-Muʾmin) 40/84-85 and Yūnus 10/90-92. I rely on that treatment.
A note, per the method (Method): the expression aw yaʾtiya rabbuka cannot be understood as a bodily coming; the same note had been entered in the index at al-Fajr 89/22. I transmit the positions taken in the classical works of tafsīr (tafwīḍ / taʾwīl), and I do not impose a preference.