الكي
Branding the skin with a heated instrument, named as effective but explicitly discouraged by the Prophet ﷺ in favor of other options — included here to show the tradition does not endorse every treatment it names.
الشِّفَاءُ فِي ثَلَاثَةٍ: شَرْطَةِ مِحْجَمٍ، أَوْ شَرْبَةِ عَسَلٍ، أَوْ كَيَّةٍ بِنَارٍ، وَأَنْهَى أُمَّتِي عَنِ الْكَيِّ
“Healing is found in three things: a cupping incision, a draught of honey, or cauterization by fire — though I discourage my community from cauterization.” (meaning, not a literal translation)
In another narration the Prophet ﷺ is reported to have said he disliked cauterization and did not like to use it (Sahih al-Bukhari 5725).
Ibn al-Qayyim reads this as permission without endorsement — cauterization remained a recognized last-resort option in classical medicine, but a discouraged one given its pain and risk of harm, to be used only once safer options were exhausted.