عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ الْأَنْصَارِيِّ رَضِيَ اللَّهُ عَنْهُ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يَقُولُ: ((مَنْ صَامَ رَمَضَانَ وَسِتًّا مِنْ شَوَّالٍ، فَكَأَنَّمَا صَامَ السَّنَةَ كُلَّهَا))
It is narrated from Sayyiduna Jabir bin Abdullah Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him and his family) said: Whoever fasts in the month of Ramadan and then follows it with six days of fasting in Shawwal, it is as if he has fasted for the whole year.