Mishkat al-Masabih 8 The Excellent Qualities of the Qur’an كتاب فضائل القرآن 80

وَعَنْ جُنْدُبِ بْنِ عَبْدُ اللَّهِ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسلم: «اقرؤوا الْقُرْآنَ مَا ائْتَلَفَتْ عَلَيْهِ قُلُوبُكُمْ فَإِذَا اخْتَلَفْتُمْ فَقومُوا عَنهُ»

Jundub b. ‘Abdallāh reported God’s messenger as saying, “Recite the Qur’ān as long as you can concentrate on it, but when your concentration flags give it up.” (Bukhārī and Muslim.)