Narrated 'Abd al-Rahman b. Abi Laila:A man from the Companions of the Prophet (ﷺ) told me that the Messenger of Allah (ﷺ) prohibited cupping and perpetual fasting, but he had not made them unlawful showing mercy on his Companions. Thereupon he was asked: Messenger of Allah, you observe perpetual fast till dawn. He replied: I observe perpetual fast till dawn (for) my Lord gives me food and drink

English translation · Sunan Abu Dawud