The Messenger of Allah (ﷺ) used to fast three days every month.
Ya’ish ibn Tikhfat al-Ghifari said: My father was one of the people in the Suffah. The Messenger of Allah (ﷺ) said: Come with us to the house of Aisha. So we went and he said: Give us food, Aisha. She brought hashishah and we ate. He then said: Give us food, Aisha. She then brought haysah as small in quantity as a pigeon and we ate. He then said: Give us something to drink, Aisha. So she brought a bowl of milk, and we drank. Again he said: Give us something to drink, Aisha. She then brought a small cup and we drank. He then said: If you wish, you may spend the night (here), or if you wish, you may go to the mosque. He said: While I was lying on my stomach because of pain in the lung, a man began to shake me with his foot and then said: This is a method of lying which Allah hates. I looked and saw that he was the Messenger of Allah (ﷺ).