وَعَنْ أَبِي الدَّرْدَاءِ
قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَيَعْجَزُ أَحَدُكُمْ أَنْ يَقْرَأَ فِي لَيْلَةٍ ثُلُثَ الْقُرْآنِ؟» قَالُوا: وَكَيْفَ يَقْرَأُ ثُلُثَ الْقُرْآنِ؟ قَالَ: «قُلْ هُوَ الله أحد» يعدل ثلث الْقُرْآن
He reported God’s messenger as saying, “Is any of you incapable of reciting a third of the Qur’an in a night?” On being asked how they could recite a third of the Qur’an he replied. “‘Say, He is God, One’ (Qur’an, 112) is equivalent to a third of the Qur’an.”
Mishkat al-Masabih 2033, Book 9, The Excellent Qualities of the Qur'an, Hadith 19. 1 min read