The Messenger of Allah ﷺ forbade cupping and continuous fasting, but he did not declare them strictly unlawful, out of consideration for his companions.It was said to him, "Messenger of Allah, you yourself fast continuously until the predawn hour."He replied, "I fast continuously until the predawn hour, and my Lord feeds me and gives me drink."
أن رسول الله ﷺ نهي عن الحجامة والمواصلة. ولم يحرمهما إبقاء على أصحابه، فقيل له: يا رسول الله إنك تواصل إلى السحر. فقال: إني أواصل إلى السحر، وربي يطعمني ويسقيني.
Abu Dawud (2374) narrated it from Imam Ahmad. It is also in his Musnad (18822), from Abdul-Rahman bin Mahdi, from Sufyan, from Abdul-Rahman bin Abis, from Abdul-Rahman bin Abu Layla, who said, a man from the companions of the Prophet ﷺ told me, and then he related it.He also narrated it (18823, 18836) from Abdul-Razzaq, and it is in his Musannaf (7535), from Sufyan with his chain, in a similar wording. Its chain of transmission is sahih, and the fact that the companion is unnamed does not harm the narration, because all the companions are trustworthy.His saying, "as mercy," means compassion. This is the reason behind the prohibition, meaning the prohibition was not because it was forbidden in itself, but out of mercy. His saying, "until suhoor," with two fatha vowels, refers to some occasions only, otherwise there is evidence indicating that he used to continue fasting for longer than that.