Someone asked, "Messenger of Allah, in how long should I complete the recitation of the Quran?"He replied, "In a month."The man said, "I am capable of more than that."Abu Musa kept repeating the exchange, with the man asking for shorter periods, until the Prophet ﷺ said, "Recite it in seven days."The man said, "I am capable of more than that."He replied, "Whoever recites it in less than three days does not understand it."
يا رسول الله، في كم أقرأ القرآن؟ قال: في شهر قال: إني أقوى من ذلك-ردد الكلام أبو موسى وتناقصه، حتى-قال: اقرأه في سبع قال: إني أقوى من ذلك، قال: لا يفقه من قرأه في أقل من ثلاث.
Abu Dawud (1390), Tirmidhi (2949), and Ibn Majah (1347) narrated it, and Ibn Hibban (758) graded it sahih, all of them through various chains from Qatada, from Yazid bin Abdullah bin Shikhir, from Abdullah bin Amr bin As, who related it. The wording given here is that of Abu Dawud. Its chain of transmission is sahih.Regarding the phrase "Abu Musa repeated the words," Abu Musa here is Muhammad bin Muthanna, the teacher of Abu Dawud, and the repeating and going back over the words took place between the Messenger of Allah ﷺ and Abdullah bin Amr bin As.