بســــــــــــــــــــــــــــــــم الله الرحمن الرحــيــم
السلام عليكم و رحمة الله وبركاته
Abu Ayyub al-Ansari narrated that Allah’s Messenger ﷺ said: “He who fasts Ramadan, and six of Shawwal, it will be (in terms of rewards) as if the fasted a whole year.” [Muslim, at-Tirmidhi, Abu Dawud, Ahmad, Ibn Majah]
“A person who has missed days of fasting in Ramadan may fast the optional six days of Shawwal with the intention of both making up for these missed days and observing the optional fasting of six days of Shawwal. He or she will then get double benefit simultaneously: making up for the missed days and getting the reward of fasting the six days of Shawwal, for it is established in Islam that one’s acts are judged by one’s intentions.However, it is recommended that one makes up for the missed fasts separately from fasting the six days of Shawwal [so as to get extra reward].” Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee.
It is highly recommended to fast six days of the month of Shawwal, but it is not obligatory. Those who want to fast can fast after `Eid Al-Fitr any six days during Shawwal. It is not required to fast six days continuously without any interruption. One can fast according to convenience any time during the month.