It is proven that the Prophet, may God’s prayers and peace be upon him, cupped while he was fasting. It was narrated by Al-Bukhari on the authority of Ibn Abbas

Abu Dawud narrated on the authority of Abu Hurairah, who said that the Messenger of God, may God’s prayers and peace be upon him, said that he vomited while he was fasting, so he does not have to make up for it. And if he vomits, let him make up for it.

The narrators of this hadith are all trustworthy.