Assalamu 'alaikum, Eid Mubarak!
Praise be to Allah and peace and blessings be upon His Messengers, our master Mohammed may Allah bless him and his family and companions and those who followed them in truth until the Day of Judgment.
Fasting six days of Shawal after the obligatory fast of Ramadan is Sunnah. It is recommended for the Muslim to fast six days of Shawal, as was reported in a saheeh hadeeth (Narrated by Muslim, Abu Dawood, al-Tirmidhi, al-Nisaa’i and Ibn Maajah) that Abu Ayyoob (may Allah be pleased with him) reported that the Messenger of Allah (peace and blessings of Allah be upon him) said:
“Whoever fasts Ramadan and follows it with six days of Shawwaal, it will be as if he fasted for a lifetime.”
The Prophet (peace and blessings of Allah be upon him) explained this when he 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).
Al-Nisaa’i and Ibn Maajah reported that the Prophet (peace and blessings of Allah be upon him) said:
“Allah has made for each hasanah ten like it, so a month is like fasting ten months, and fasting six days completes the year.”.
It was also narrated by Ibn Khuzaymah with the wording: “Fasting for the month of Ramadan brings the reward of ten like it, and fasting for six days brings the reward of two months, and that is the fasting of the whole year.”
Another of the important benefits of fasting six days of Shawal 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 naafil deeds will be taken to make up the shortcomings in his obligatory deeds, as the Prophet (peace and blessings of Allah be upon him) said:
“The first thing for which people will be brought to account on the Day of Resurrection will be their salaah (prayer). Our Lord, may He be glorified and exalted, will say to His angels – although He knows best – ‘Look at the salaah 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 (naafil) 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.” (Narrated by Abu Dawood).
When should a Muslim start fasting six days of Shawal?
Muslim can start fasting six days of Shawal from the second day of Shawal, because it is haraam to fast on the day of Eid. You can fast the six days at any time during Shawal, although the best of good deeds are those which are done soonest.
Is It valid to combine making up missed Ramadan fasts with fasting six days of Shawal with one intention?
That is not valid, because fasting the six days of Shawal can only be done after fasting Ramadan in full. And Allah knows the best.
May Allah accept our good deeds and forgive us.
Mohsen Shaker Bayoumy
Imam of Osaka Ibaraki Mosque