Abu Ayyub (may Allah be pleased with him) reported that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever fasts Ramadhan and follows it with six days of Shawwal, it will be as if he fasted for a lifetime." [Narrated by Muslim, Abu Dawud, at-Tirmidhi, an-Nisa'i and Ibn Majah]