Narrated Abdullah ibn Amr ibn al-'As:

Wahb ibn Munabbih said: Abdullah ibn Amr asked the Prophet ﷺ; In how many days should one complete the recitation of the Qur'an? He said: In forty days. He then said: In one month. He again said: In twenty days. He then said: In fifteen days. He then said: In ten days. Finally he said: In seven days.

حَدَّثَنَا نُوحُ بْنُ حَبِيبٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ سِمَاكِ بْنِ الْفَضْلِ، عَنْ وَهْبِ بْنِ مُنَبِّهٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، أَنَّهُ سَأَلَ النَّبِيَّ ﷺ فِي كَمْ يَقْرَأُ الْقُرْآنَ قَالَ " فِي أَرْبَعِينَ يَوْمًا " . ثُمَّ قَالَ " فِي شَهْرٍ " . ثُمَّ قَالَ " فِي عِشْرِينَ " . ثُمَّ قَالَ " فِي خَمْسَ عَشْرَةَ " . ثُمَّ قَالَ " فِي عَشْرٍ " . ثُمَّ قَالَ " فِي سَبْعٍ " . لَمْ يَنْزِلْ مِنْ سَبْعٍ .