Prayer (Kitab Al-Salat): Detailed Injunctions about Ramadan
Dawud :: Book 6 : Hadith 1390
Narrated Abdullah ibn Amr ibn al-'As:
Wahb ibn Munabbih said: Abdullah ibn Amr asked the Prophet (peace_be_upon_him); 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.