Albert Barnes Commentary Judges 3:31

"And after him was Shamgar the son of Anath, who smote of the Philistines six hundred men with an ox-goad: and he also saved Israel." — Judges 3:31 (ASV)

From this verse and (Judges 5:6) we may gather that Shamgar was contemporary with Jael, and that he only procured a temporary and partial deliverance for Israel by his exploit. He may have been of the tribe of Judah.

An ox goad: An instrument of wood about eight feet long, armed with an iron spike or point at one end, with which to spur the ox at the plow, and with an iron scraper at the other end with which to detach the earth from the plowshare when it became encumbered with it. The fact of their deliverer having no better weapon enhances his faith, and the power of his divine helper. At the same time, it shows how low the men of Judah were brought at this time, being disarmed by their oppressors (Judges 5:8), as was also the case later (1 Samuel 13:19).