It was narrated from Jabir bin Samurah that a man from among the Companions of the Prophet (ﷺ) was wounded, and the wound caused him a great deal of pain. He went and took a spearhead, and slaughtered himself with it. The Prophet (ﷺ) did not offer the funeral prayer for him, and that was as an admonition for others.
Sunan Ibn Majah Book 6, Hadith 94