"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.'"
Jami` at-Tirmidhi Book 8, Hadith 87
← Previous Hadith "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)."

Jami` at-Tirmidhi Book 8, Hadith 86 Next Hadith → 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."

Jami` at-Tirmidhi Book 8, Hadith 88