Kathir narrated to him that the Prophet ﷺ used to be cupped on the crown of his head and between his shoulders, and he would say, "Whoever lets out some of this blood, it will not harm him if he does not seek any other remedy for any ailment."
حدثنا عبد الرحمن بن إبراهيم الدمشقي وكثير بن عبيد قالا حدثنا الوليد عن ابن ثوبان عن أبيه
كثير إنه حدثه أن النبي ﷺ كان يحتجم على هامته وبين كتفيه وهو يقول من أهراق من هذه الدماء فلا يضره أن لا يتداوى بشيء لشيء
[Its chain is daif]. Ibn Majah narrated it in his chapter on medicine, in the section on the location for cupping, no. 3484, from the hadith of Walid bin Muslim, with the same wording, but he did not clearly state that the chain of transmission was uninterrupted throughout.