Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) said to me: "Recite the Qur'an in forty days." Then he said, "Recite it in thirty days." Then he said, "Recite it in twenty days." Then he said, "If not, then in fifteen days." Then he said, "If not, then in ten days." Or, "Then in seven days." The Prophet (peace and blessings be upon him) concluded the matter at seven days.

Sayyiduna Abdullah bin Amr (may Allah be pleased with him) says: I said: O Messenger of Allah! In how many days should I complete the recitation of the Qur'an? The Prophet (peace and blessings of Allah be upon him) said: "Complete the Qur'an in every month." I said: I am able to do more than that. The Prophet (peace and blessings of Allah be upon him) said: "Then in twenty-five days." ... "Or then in twenty days." ... "Alright, then in fifteen days." ... "If not, then in seven days, (but) whoever completes the Qur'an in less than three days, he has not understood it."

Lady Aisha (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) did not complete the recitation of the Qur'an in less than three days.