The Messenger of Allah ﷺ forbade cauterization, but we cauterized ourselves anyway, and it neither succeeded nor brought us any benefit.
حدثنا عبد الله حدثني أبي حدثنا عفان حدثنا حماد حدثنا ثابت عن مطرف
أن رسول الله ﷺ نهى عن الكي فاكتوينا فلم يفلحن ولم ينجحن
Its isnad is sahih. It has already appeared at 19750. As for his saying "lam yuflihna" ("they did not succeed"), he made the pronoun refer back to an implied, elided antecedent, meaning the cauterizations by which the sick person is cauterized.