They slew every one his man, i.e. him who came to fight with him, or to seize upon him, as Ben-hadad had commanded. The Syrians fled; being amazed at the unexpected and undaunted courage of the Israelites, and being struck with a Divine terror.
Related Commentaries of 1 Kings 20:20
1 Kings 20:20
20 And they slew every one his man: and the Syrians fled; and Israel pursued them: and Benhadad the king of Syria escaped on an horse with the horsemen.