MUSLIM 1159d:
from Qāl —
The Messenger of Allah ﷺ said to me: Recite the whole of the Qur'An during every month. I said: I find power (to recite it) in a shorter period. He said: Then recite it in twenty nights. I said: I find power (to recite it in a shorter period even than this), whereupon he said: Then recite it in seven (nights) and do not exceed beyond it.
مسلم ١١٥٩d:
عن قال —
وَأَحْسِبُنِي قَدْ سَمِعْتُهُ أَنَا مِنْ أَبِي سَلَمَةَ عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو ؓ قَالَ قَالَ لِي رَسُولُ اللَّهِ ﷺ اقْرَإِ الْقُرْآنَ فِي كُلِّ شَهْرٍ قَالَ قُلْتُ إِنِّي أَجِدُ قُوَّةً قَالَ فَاقْرَأْهُ فِي عِشْرِينَ لَيْلَةً قَالَ قُلْتُ إِنِّي أَجِدُ قُوَّةً قَالَ فَاقْرَأْهُ فِي سَبْعٍ وَلاَ تَزِدْ عَلَى ذَلِكَ