I asked or someone asked the Prophet (ﷺ) about perpetual fasting. He replied: You have a duty to your family. Fast during Ramadan and the following month, and every Wednesday and Thursday. You will then have observed a perpetual fast.

The Prophet (ﷺ) as saying: If anyone fasts during Ramadan, then follows it with six days in Shawwal, it will be like a perpetual fast.

The Messenger of Allah (ﷺ) used to fast to such an extent that we thought that he would never break his fast, and he would go without fasting to such an extent that we thought he would never fast. I never saw the Messenger of Allah (ﷺ) fast a complete month except in Ramadan, and I never saw his fast more in any month than in Sha'ban.

He would fast all but a little of Sha'ban, rather he used to fast the whole of Sha'ban.

The client of Usamah ibn Zayd said that he went along with Usamah to Wadi al-Qura in pursuit of his camels. He would fast on Monday and Thursday. His client said to him: Why do you fast on Monday and Thursday, while you are an old man? He said: The Prophet of Allah (ﷺ) used to fast on Monday and Thursday. When he was asked about it, he said: The works of the servants (of Allah) are presented (to Allah) on Monday and Thursday.

Hunaydah ibn Khalid narrated from his wife on the authority of one of the wives of the Prophet (ﷺ) who said: The Messenger of Allah (ﷺ) used to fast the first nine days of Dhul-Hijjah, Ashura' and three days of every month, that is, the first Monday (of the month) and Thursday.

The Messenger of Allah (ﷺ) as saying: There is no virtue more to the liking of Allah in any day than in these days, that is, the first ten days of Dhu al-Hijjah. They (the Companions) asked: Messenger of Allah, not even the struggle in the path of Allah (Jihad) ? He said: (Yes), not even the struggle in the path of Allah, except a man who goes out (in the path of Allah) with his life and property, and does not return with any of them.

I never saw the Messenger of Allah (ﷺ) fasting during the first ten days of Dhu al-Hijjah.

Ikrimah said: We were with AbuHurayrah in his house when he narrated to us: The Messenger of Allah (ﷺ) prohibited fasting on the day of Arafah at Arafah.

On the day of 'Arafah some people near her argued whether the Messenger of Allah (ﷺ) was fasting, some saying that he was, and others saying that he was not. I, therefore, sent him a cup of milk while he was observing the halt at 'Arafah on his camel, and he drank it.

The Quraish used to fast on the day of 'Ashurah in pre Islamic days. The Messenger of Allah (ﷺ) would fast on it in pre-Islamic period. When the Messenger of Allah (ﷺ) came to Medina, he fasted on it and commanded to fast on it. When the fast of Ramadan was prescribed, that became obligatory, and (fasting on) 'Ashurah was abandoned. He who wishes may fast on it and he who wishes may leave it.

'Ashurah was a day on which we used to fast in pre-Islamic days. When (fasting of) Ramadan was prescribed, the Messenger of Allah (ﷺ) said: This is one of the days of Allah ; he who wishes may fast on it.

When the Prophet (ﷺ) came to Medina, he found the Jews observing fast on the day of 'Ashurah; so they were asked about it (by the Prophet). They said: This is a day on which Allah gave Moses domination over Pharaoh. We fast on it out of reverence to him. The Messenger of Allah (ﷺ) said: We have a closer connection with Moses than you have. He then gave orders that it should be observed.

When the Prophet (ﷺ) on the day of 'Ashurah and commanded us to fast on it, they (i.e. Companions) said: Messenger of Allah, this is a day which is considered great by Jews and Christians ? The Messenger of Allah (ﷺ) said: When the next year comes, we shall fast on the 9th of Muharram. But the next year the Messenger of Allah (ﷺ) breathed his last.

I came to Ibn 'Abbas who was leaning against his sheet of cloth in the Sacred Mosque (al-Masjid al-Haram). I asked him about fasting on the day of 'Ashurah. He said: When you sight the moon of al-Muharram, count (the days). When the 9th of Muharram comes, fast from the morning. I said: Would Muhammad (ﷺ) observe this fast ? He replied: Thus Muhammad (ﷺ) used to fast.

AbdurRahman reported on the authority of his uncle that the people of the tribe Aslam came to the Prophet (ﷺ). He said (to them): Did you fast on this day? They replied: No. He said: Complete the rest of your day, and make atonement for it.

The Messenger of Allah (ﷺ) said to me: The fast most liked by Allah is the one observed by Dawud (David), and the prayer dearer to Allah is the one offered by Dawud (David): he would sleep half the night, and stand (in prayer) one-third of it, and sleep one-sixth of it. He would go without fasting one day, and fast the other day.

The Messenger of Allah (ﷺ) used to command us to fast the days of the white (nights): thirteenth, fourteenth and fifteenth of the month. He said: This is like keeping perpetual fast.

The Messenger of Allah (ﷺ) used to fast three days every month.

The apostle of Allah (ﷺ) used to fast three days every month: Monday, Thursday and Monday in the next week.