Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
muslim:789b – [Chain 1] Zuhayr b. Ḥarb And Muḥammad b. al-Muthanná Waʿubayd Allāh b. Saʿīd > Yaḥyá Wahū al-Qaṭṭān [Chain 2] Abū Bakr b. Abū Shaybah > Abū Khālid al-Aḥmar [Chain 3] Ibn Numayr > Abū > ʿUbaydullāh [Chain 4] Ibn Abū ʿUmar > ʿAbd al-Razzāq > Maʿmar > Ayyūb [Chain 5] Qutaybah b. Saʿīd > Yaʿqūb / Ibn ʿAbd al-Raḥman [Chain 6] Muḥammad b. Isḥāq al-Musayyabī > Anas / Ibn ʿIyāḍ > Mūsá b. ʿUqbah Kul Haʾulāʾ > Nāfiʿ > Ibn ʿUmar

" When one who had committed the Qur'an to memory (or who is familiar with it) gets up (for night prayer) and recites it night and day, it remains fresh in his mind, but if he does not get up (for prayer and thus does not recite it) he forgets it."  

مسلم:٧٨٩b – حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ وَمُحَمَّدُ بْنُ الْمُثَنَّى وَعُبَيْدُ اللَّهِ بْنُ سَعِيدٍ قَالُوا حَدَّثَنَا يَحْيَى وَهُوَ الْقَطَّانُ ح وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ حَدَّثَنَا أَبُو خَالِدٍ الأَحْمَرُ ح وَحَدَّثَنَا ابْنُ نُمَيْرٍ حَدَّثَنَا أَبِي كُلُّهُمْ عَنْ عُبَيْدِ اللَّهِ ح وَحَدَّثَنَا ابْنُ أَبِي عُمَرَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ أَخْبَرَنَا مَعْمَرٌ عَنْ أَيُّوبَ ح وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ حَدَّثَنَا يَعْقُوبُ يَعْنِي ابْنَ عَبْدِ الرَّحْمَنِ ح وَحَدَّثَنَا مُحَمَّدُ بْنُ إِسْحَاقَ الْمُسَيَّبِيُّ حَدَّثَنَا أَنَسٌ يَعْنِي ابْنَ عِيَاضٍ جَمِيعًا عَنْ مُوسَى بْنِ عُقْبَةَ كُلُّ هَؤُلاَءِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ

عَنِ النَّبِيِّ بِمَعْنَى حَدِيثِ مَالِكٍ وَزَادَ فِي حَدِيثِ مُوسَى بْنِ عُقْبَةَ وَإِذَا قَامَ صَاحِبُ الْقُرْآنِ فَقَرَأَهُ بِاللَّيْلِ وَالنَّهَارِ ذَكَرَهُ وَإِذَا لَمْ يَقُمْ بِهِ نَسِيَهُ  

See similar narrations below:

Collected by Suyūṭī