Saad bin Muaz was struck by an arrow in his median vein. The Prophet ﷺ cauterized the wound with his own hand using a broad-headed arrow. Then it swelled, so he cauterized it a second time.
رمي سعد بن معاذ في أكحله قال: فحسمه النبي ﷺ بيده بمشقص ثم ورمت، فحسمه الثانية.
Muslim narrated it in the Book of Greetings (2208), by way of Abu Khaythama (Zuhayr bin Muawiya), from Abu Zubayr, from Jabir, and he mentioned it.His saying, "his akhal" refers to a vein in the forearm from which blood is drawn. His saying, "and he cauterized it" means he seared it with heat.