Sahih al-Bukhari 2279Book 37, Hadith 19
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ خَالِدٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ احْتَجَمَ النَّبِيُّ صلى الله عليه وسلم وَأَعْطَى الْحَجَّامَ أَجْرَهُ، وَلَوْ عَلِمَ كَرَاهِيَةً لَمْ يُعْطِهِ.
When the Prophet (ﷺ) was cupped, he paid the man who cupped him his wages. If it had been undesirable he would not have paid him.