مشكوة المصابيح
Mishkat al-Masabih
كتاب الصلاة
The Book of Prayer
(نِسْيَانُ آيَةٍ أَوْ سُورَةٍ بَعْدَ حِفْظِهَا ذَنْبٌ كَبِيرٌ)
(Forgetting a verse or a surah after memorizing it is a major sin)
Hadith 720
وَعَنْ أَنَسِ بْنِ مَالِكٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسلم: «عُرِضَتْ عَلَيَّ أُجُورُ أُمَّتِي حَتَّى الْقَذَاةُ يُخْرِجُهَا الرَّجُلُ مِنَ الْمَسْجِدِ وَعُرِضَتْ عَلَيَّ ذُنُوبُ أُمَّتِي فَلَمْ أَرَ ذَنْبًا أَعْظَمَ مِنْ سُورَةٍ مِنَ الْقُرْآنِ أَوْ آيَةٍ أُوتِيهَا رَجُلٌ ثُمَّ نَسِيَهَا» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُد
He also reported God’s Messenger as saying, “The rewards of my people were placed before me, even [for] a speck of dust a man takes out of the mosque] and the sins of my people were placed before me, and I saw no sin greater than that a man should memorise a sura or verse of the Qur’an, then forget it."* * Cf. Al-Qur’an, 20:126. Tirmidhi and Abu Dawud transmitted it.
