It is narrated from Sayyiduna Sahl bin Hunayf (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) went to visit Sayyiduna As'ad bin Zurarah (may Allah be pleased with him), who was suffering from an illness called "al-shawkah". He (peace and blessings be upon him) cauterised him on his shoulder, and then he died. At that, the Messenger of Allah (peace and blessings be upon him) said: "(This is) the worst death for the Jews; they will say: His companion (meaning Muhammad, peace and blessings be upon him) treated him, but it did him no good."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5562