Virtues of fasting during Shawwal

Shawwal means ‘lift or carry.’ Shawwal is the tenth month on the Lunar Islamic calendar. The first day of Shawwal is Eid Al-Fitr. There are also six days of fasting during Shawwal which, together with the Ramadan fasts, are equivalent to fasting “perpetually.”
The Prophet Muhammad (peace be upon him) said: “He who observed the fast of Ramadan and then followed it with six (fasts) of Shawwal. It would be as if he fasted perpetually.” (Muslim)
The Islamic calendar is a lunar calendar, and months begin when the first crescent of a new moon is sighted. Since the Islamic lunar calendar year is 11 to 12 days shorter than the solar year, Shawwal migrates throughout the seasons.
Beginning of the Ashur-Al-Haj
Shawwal is the first of the three months named as “Ashur Al-Haj” (i.e. the months of Haj). Although the major acts of Haj are normally performed in the first ten days of Dhul Haj, yet the whole period starting from the first of Shawwal up to the 10th of Dhul-Haj is held to be the period of Haj because some acts of Haj can be performed any time during this period. For example, the Tawaf Al-Qudum, followed by the Sai’ of Haj cannot be performed before Shawwal, while it can be performed any day after the beginning of Shawwal. Similarly, an Umrah performed before Shawwal cannot be treated as the Umrah of Tamattu: While the Umrah performed in Shawwal can be affiliated to the Haj, making it a Haj of Tamattu. Ihram of Haj should not be started before Shawwal, because it makrooh. For these reasons these three months have been named as the ‘months of Haj' and the month of Shawwal has the distinction of being the first of these.
Virtues of fast for six days in Shawwal
It is commendable to keep six fasts in the month of Shawwal. Muslims should take this opportunity of acquiring such an enormous reward from Allah. It is more preferable to start these fasts from the 2nd of Shawwal and keep fasting up to the 7th of it.
However, if, they are kept in other days, the requirement also be fulfilled. The sooner you do them, the better.
Allah, the Exalted says: “And march forth in the way (which leads to) forgiveness from your Lord." (Qur'an, 3:133)
“I hastened to you, O my Lord, that you might be pleased.” (Qur'an, 20:84)
Muslim should hasten to fast these six days of Shawwal because delaying may cause problems, but there is no problem if you do not hasten it and you delay it until the middle or end of the month.
The Prophet Muhammad (peace be upon him) said: “He who fasts Ramadan, and six of Shawwal, it will be (in terms of rewards) as if the fasted a whole year.” (Abu Dawud, Ahmad, Ibn Majah, Muslim and Tirmidhi)
In commenting on the above-mentioned Hadith, As-Sananee said in Subul us-Salaam: “If the thirty days of Ramadan fasting are assimilated with the six days of fasting in Shawwal, it altogether makes 36 days. According to Shari’ah, each virtue is rewarded ten times. Therefore, if we multiply 36 with 10, it makes 360 which slightly longer than a lunar year and next Ramadan he will fast again so it is as if he fasted his whole life.
The Prophet Muhammad (peace be upon him) said: “If one keeps the fasts of Ramadan throughout his life and keeps six consecutive fasts in Shawwal it will be as though he has kept a whole life time of fasts, and if one fasts for six consecutive days in Shawwal it will be as though he has fasted all year round.” (Muslim)
Women should first make up her missed fasts from Ramadan due to her monthly period and if she wants to earn the reward mentioned in the above Hadith, then she should follow it with six days of Shawwal, and she will gain the reward mentioned in it. It is also permissible for women to delay making up her Ramadan fasts, as long as she makes them up before the next Ramadan comes.
The Prophet Muhammad (peace be upon him) said: “The one, who fast in the month of Ramadan and then during six days of Shawwal, is as purified of sins as he was born just today.” (Abu Dawud and Muslim)
Fasting six days of Shawwal after the obligatory fast of Ramadan is Sunnah Mustahab, not wajib.
The Prophet Muhammad (peace be upon him) said: “Whoever fasts for six days after (Eid) Al-Fitr has completed the year: (Whoever does a good deed (Hasanah) will have ten Hasanah like it).” According to another report: “Allah has made for each Hasanah ten like it, so a month is like fasting ten months, and fasting six days completes the year.” (Al-Nisaa’i, Ibn Majah and Targheeb Wal Tarheeb)
Benefits of fasting in Shawwal
The important benefits of fasting six days of Shawwal is that is makes up for any shortfall in a person’s obligatory Ramadan fasts, because no one is free of shortcomings or sins that have a negative effect on his fasting. On the Day of Resurrection, some of his nafil deeds will be taken to make up the shortcomings in his obligatory deeds.
The Prophet Muhammad (peace be upon him) said: “The first thing for which people will be brought to account on the day of resurrection will be their salah (prayer).
Our Lord, may He be glorified and exalted, will say to his angels — although He knows best – ‘look at the salah of My slave, whether it is complete or incomplete.’ if it is perfect, it will be recorded as perfect, and if something is lacking, He will say, ‘Look and see whether my slave did any voluntary (nafil) prayers.’ if he did some voluntary prayers, [Allah] will say, complete the obligatory actions of My slave from his voluntary actions.’ Then all his actions will be dealt with in a similar manner.” (Abu Dawud).