Keep refreshing your knowledge of the sacred books (or always renew your knowledge of these sacred books) and sometimes he would mention the Qur'an for it is more apt to escape from men's minds than animals which are hobbled, and the Messenger of Allah ﷺ said: None of you should say: I forgot such and such a verse, but he has been made to forget.
عَبْدُ اللَّهِ تَعَاهَدُوا هَذِهِ الْمَصَاحِفَ وَرُبَّمَا قَالَ الْقُرْآنَ فَلَهُوَ أَشَدُّ تَفَصِّيًا مِنْ صُدُورِ الرِّجَالِ مِنَ النَّعَمِ مِنْ عُقُلِهِ قَالَ وَقَالَ رَسُولُ اللَّهِ ﷺ لاَ يَقُلْ أَحَدُكُمْ نَسِيتُ آيَةَ كَيْتَ وَكَيْتَ بَلْ هُوَ نُسِّيَ