It is narrated from Sayyiduna Ibn Amr (may Allah be pleased with him) that I once submitted in the presence of the Messenger of Allah, "O Messenger of Allah! In how many days should I recite the Qur'an?" The Noble Prophet (peace and blessings be upon him) said: "In one month." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Recite it in twenty-five days." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Recite it in twenty days." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Recite it in fifteen days." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Recite it in ten days." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Recite it in seven days." I said, "I have the strength for more than that." The Noble Prophet (peace and blessings be upon him) said: "Whoever recites the Qur'an in less than three days has not understood it."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6546