What a wretched person is he amongst them who says: I have forgotten such and such a verse. (He should instead of using this expression say): I have been made to forget it. Try to remember the Qur'an for it is more apt to escape from men's minds than a hobbled camel. (Using translation from Muslim 790a)
اسْتَذْكِرُوا الْقُرْآنَ فَلَهُوَ أَشَدُّ تَفَصِّيًا مِنْ صُدُورِ الرِّجَالِ مِنَ النَّعَمِ مِنْ عُقُلِهِ وَلَا يَقُولَنَّ أَحَدُكُمْ نَسِيتُ آيَةَ كَيْتَ وَكَيْتَ قَالَ قَالَ رَسُولُ اللهِ ﷺ «بَلْ هُوَ نُسِّيَ»