"The Messenger of Allah said: 'Whoever fasts three days in every month, then that is (similar to) fasting every day.' Then Allah Mighty and Sublime is He, attested to that in His Book, by revealing: Whoever brings a good deed, shall have ten times the like thereof. So a day is like ten."
"I heard Mu'adhah saying to Aishah: 'Did the Messenger of Allah fast three days of every month?' She replied in the affirmative. So she said: 'Which of them would he fast?' She said: 'Which of them he would fast was not noticeable.'"
The Messenger of Allah said: "Indeed your Lord said: 'Every good deed is rewarded with ten of the same up to seven hundred times over. Fasting is for Me, and I shall reward for it.' Fasting is a shield from the Fire. The smell coming from the mouth of the one fasting is more pleasant to Allah than the scent of musk. If one of you is abused by an ignorant person while fasting, then let him say: 'Indeed I am fasting.'"
The Prophet said: "There is a gate in Paradise called Ar-Raiyyan, those who fast shall be invited into it, and whoever was among those who fasted, then he will enter it; and whoever enters it, he will never thirst again."
"It was said: 'O Messenger of Allah! What is the case of the one who fasts daily?' He said: 'He did not fast nor break (the fast).'" Or, he said: "He never fasted nor broke (his fast)."
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَيُّوبَ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، قَالَ سَأَلْتُ عَائِشَةَ عَنْ صِيَامِ النَّبِيِّ، صلى الله عليه وسلم قَالَتْ كَانَ يَصُومُ حَتَّى نَقُولَ قَدْ صَامَ وَيُفْطِرُ حَتَّى نَقُولَ قَدْ أَفْطَرَ . قَالَتْ وَمَا صَامَ رَسُولُ اللَّهُ صلى الله عليه وسلم شَهْرًا كَامِلاً إِلاَّ رَمَضَانَ . وَفِي الْبَابِ عَنْ أَنَسٍ وَابْنِ عَبَّاسٍ . قَالَ أَبُو عِيسَى حَدِيثُ عَائِشَةَ حَدِيثٌ حَسَنٌ صَحِيحٌ .
"I asked Aishah about the Prophet's fasting.' She said: 'He would fast until we said: "He has fasted" and he would abstain from fasting until we said: "He has abstained from fasting." (She said:) 'The Messenger of Allah did not fast an entire month except Ramadan.'"
Anas bin Malik was asked about the Prophet's fasting and he said: "He would fast during a month until we thought that he did not want to abstain from fasting during any of it. And, he would not fast during a month until we thought that he did not want to fast during any of it. (There was no time) that I wanted to see if he was performing Salat during the night, except that I would see him praying, nor to see him sleeping, except that I would see him sleeping."
The Messenger of Allah said: "The most virtuous fast is the fast of my brother Dawud. He would fast a day, and not fast (the next) day. He would not flee at the time of engagement (with the enemy)."
"I witnessed Umar bin Al-Khattab on the Day of Nahr beginning with the Salat before the Khutbah. Then he said: 'I heard the Messenger of Allah prohibit fasting on these two days. As for the Day of Fitr, then it is for you to take a break from your fasting, and a celebration for the Muslims. As for the Day of Adha, then eat from the flesh that you have sacrificed.'"