Fasting the 6 days of Shawwal - equal a year of fasts
Allaah `azza wa jall, says in the Qur'aan, what means: "Say (O Muhammad): 'If you (really) love Allaah then follow me, Allaah will love you and forgive you your sins. And Allaah is Oft-Forgiving, Most Merciful." [al-Qur'aan, 3:31]
This is a beautiful verse, named by some of the salaf as "the verse of the test", as it tests how true one's love of Allaah is. They explained that if one loves Allaah, then he must show that in his/her following of the Prophet Muhammad, sallallaahu `alayhi wa sallam. The verse tells us that those who follow the Prophet, sallallaahu `alayhi wa sallam, if sincere, can in shaa' Allaah expect the following two:
Allaah ta`aalaa loving them
Allaah ta`aalaa forgiving their sins.
One of the ways to manifest our loving of Allaah, by following the Prophet, sallallaahu `alayhi wa sallam, is to do those acts that he, sallallaahu `alayhi wa sallam, advised his Companions, and the Ummah in general, to do. A sunnah which is certainly relevant to us in these days is his, sallallaahu `alayhi wa sallam, practice to fast six days in the month of Shawwaal.
Aboo Ayyoob al-Ansaaree narrated: Allaah's Messenger, sallallaahu `alayhi wa sallam, said: "He who fasts Ramadhaan, and six of Shawwaal, it will be (in terms of rewards) as if the fasted a whole year." [Reported by Muslim, at-Tirmidhee, Aboo Daawood, Ahmad, Ibn Maajah]