I put my life in my hands - Compare 1 Samuel 19:5; 1 Samuel 28:21. The phrase expresses the utmost possible risk, knowingly incurred.
Related Commentaries of Judges 12:3
Judges 12:3
3 And when I saw that ye delivered me not, I put my life in my hands, and passed over against the children of Ammon, and the LORD delivered them into my hand: wherefore then are ye come up unto me this day, to fight against me?