‘Abdallah b. Mas'ud said that God’s messenger used to fast the first three days every month, and he would seldom break his fast on a Friday.
Tirmidhi and Nasa’i transmitted it, and Abu Dawud transmitted up to “three days every month.”
‘A'isha said that God’s messenger used to fast on Saturday, Sunday, and Monday one month, and on Tuesday, Wednesday, and Thursday the next.
Tirmidhi transmitted it.
Umm Salama said that God’s messenger used to command her to fast three days every month beginning with Monday or Thursday.
Abu Dawud and Nasa’i transmitted it.
Muslim al-Qurashi said that he or someone else asked God's messenger about perpetual fasting, and 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."
Abu Dawud and Tirmidhi transmitted it.
‘Abdallah b. Busr, on the authority of his sister as-Samma’, reported God’s messenger as saying, “Do not fast on Saturday except during what has been made obligatory for you; and if one of you can get nothing but a grape skin or a piece of wood from a tree, he should chew it.”
Ahmad, Abu Dawud, Tirmidhi, Ibn Majah and Darimi transmitted it.
Abu Umama reported God’s messenger as saying, "If anyone fasts for a day while on jihad,* God will put between him and hell a ditch as wide as the distance between heaven and earth."
*Mirqat gives this meaning, but says it may refer to the hajj, the 'umra, seeking knowledge, or desiring to please God. The Arabic is 'in God’s way.'
Tirmidhi transmitted it.
‘Amir b. Mas'ud reported God’s messenger as saying, “Fasting in winter is booty gained without trouble.”*
*Literally, 'the cold booty.' The idea is that in winter one does not suffer from hunger and thirst as in summer.
Ahmad and Tirmidhi transmitted it, the latter saying this is a mursal tradition.
The tradition of Abu Huraira, “No days are dearer to God”, has been mentioned in the chapter on the sacrifices.*
*Reference to the first ten days of the month of Dhul Hijjah.
Ibn ‘Abbas said that God’s messenger came to Medina and found the Jews observing the fast on the day of ‘Ashura’, so he asked them what was the significance of that day which they were observing and they replied, “It is a great day on which God delivered Moses and his people and drowned Pharaoh and his people; so Moses observed it as a fast out of gratitude, and we do so also.” He said, “We have more right, and we have a closer connection with Moses than you have,” so God’s messenger observed it as a fast himself and gave orders that it should be observed.
(Bukhari and Muslim.)
Umm Salama said that God's messenger used to fast on Saturdays and Sundays more than on other days, and he used to say, “They are days of festival for the polytheists, and I like to act contrary to them.”
Ahmad transmitted it.
Jabir b. Samura said, “God’s messenger used to command us to observe the day of ‘Ashura’ as a fast, urge us to observe it and pay attention to us when it came; but when Ramadan was made obligatory he neither commanded nor forbade us to observe it, nor did he pay attention to us when it came.”
Muslim transmitted it.
Hafsa said there were four things the Prophet (ﷺ) never omitted: fasting on ‘Ashura’, the first ten days of Dhul Hijja* and three days every month, and praying two rak'as before dawn.
*The Arabic has simply 'the ten', to be understood as translated above.
Nasa’i transmitted it.
Ibn ‘Abbas said that it was the custom of God’s messenger not to eat on the middle days* of the month whether travelling or not.
*Literally, the days of the white (nights). These are the days following the thirteenth, fourteenth, and fifteenth nights of the month, the nights when there is most moonlight.
Nasa’i transmitted it.
Abu Huraira reported God’s messenger as saying, “There is zakat applicable to everything, and the zakat of the body is fasting.”
Ibn Majah transmitted it.
He said that the Prophet (ﷺ) used to fast on Mondays and Thursdays, and when someone remarked on this to him he said, “On Monday and Thursday God forgives every Muslim except two who are at variance, for He says they must be left till they make peace with one another.”
Ahmad and Ibn Majah transmitted it.
He reported God’s messenger as saying, “If anyone out of a desire to please God fasts for a day, God will remove him from jahannam as far as a crow flies from the time it is a young bird till it dies of old age.”
Ahmad transmitted it, and Baihaqi transmitted it in Shu'ab al-iman from Salama b. Qais.
‘A'isha said: The Prophet (ﷺ) came to visit me one day and asked if I had anything [to eat]. When I said I had nothing he replied, “Then I shall observe a fast.” When he came to me another day and I told him I had been given a present of some hais* he said, “Show me it, for I began the day fasting.” Then he ate.
*A mixture of dates and clarified butter.
Muslim transmitted it.
Anas said that the Prophet (ﷺ) visited Umm Sulaim, and when she brought him some dates and clarified butter he said, “Put your butter back in its container and your dates in their vessel, for I am fasting.” He then went to a separate part of the house and prayed a prayer which was not one of the prescribed prayers, and invoked a blessing on Umm Sulaim and the inhabitants of her house.
Bukhari transmitted it.
Abu Huraira reported God’s messenger as saying, “When one of you is invited to a meal at a time when he is fasting he should say he is fasting.” In a version he said, “When one of you receives an invitation he should accept it. If he is fasting he should pray, but if not, he should eat.”
Muslim transmitted it.