Mishkat al-Masabih 7 Fasting كتاب الصوم 60

وَعَنْ ثَابِتٍ الْبُنَانِيِّ قَالَ: سُئِلَ أَنَسُ بْنُ مَالِكٍ: كُنْتُمْ تَكْرَهُونَ الْحِجَامَةَ لِلصَّائِمِ عَلَى عَهْدِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ؟ قَالَ: لَا إِلَّا مِنْ أَجْلِ الضَّعْفِ. رَوَاهُ الْبُخَارِيُّ

Thabit al-Bunani said that when Anas b. Malik was asked whether they disapproved of cupping for one who was fasting in the time of God’s messenger he replied, “No, except if it had a weakening effect.” Bukhari transmitted it.