Sunan an-Nasa'i 943
سنن النسائي#943Sahihأَخْبَرَنَا عِمْرَانُ بْنُ مُوسَى، قَالَ حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " بِئْسَمَا لأَحَدِهِمْ أَنْ يَقُولَ نَسِيتُ آيَةَ كَيْتَ وَكَيْتَ بَلْ هُوَ نُسِّيَ اسْتَذْكِرُوا الْقُرْآنَ فَإِنَّهُ أَسْرَعُ تَفَصِّيًا مِنْ صُدُورِ الرِّجَالِ مِنَ النَّعَمِ مِنْ عُقُلِهِ ".
It was narrated from Abdullah that:The Prophet (ﷺ) said: "It is not right for any one of you to say: 'I have forgotten such and such a verse.' Rather, he has been caused to forget. Study the Qur'an, for it escapes from the heart of man faster than a camel escapes from its fetter
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: 11:68