Sahih al-Bukhari, Hadith 2103 ⓘ
Narrated Ibn `Abbas: Once the Prophet got his blood out (medically) and paid that person who had done it. If it had been illegal, the Prophet would not have paid him.
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا خَالِدٌ ـ هُوَ ابْنُ عَبْدِ اللَّهِ ـ حَدَّثَنَا خَالِدٌ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ احْتَجَمَ النَّبِيُّ صلى الله عليه وسلم وَأَعْطَى الَّذِي حَجَمَهُ، وَلَوْ كَانَ حَرَامًا لَمْ يُعْطِهِ.
also referenced under: Book 34, Hadith 56 (In-Book) & Volume 3, Book 34, Hadith 316 (USC-MSA)