Charles Ellicott Commentary 2 Kings 6:31

"Then he said, God do so to me, and more also, if the head of Elisha the son of Shaphat shall stand on him this day." — 2 Kings 6:31 (ASV)

Then he said. — And he (that is, the king), said.

God do so ... to me. — Literally, So may God do to me, and so may he add: a common form of oath. (1 Samuel 3:17; 1 Kings 2:23.)

If the head of Elisha ... this day. — The king’s horror at the woman’s dreadful story is succeeded by indignation against Elisha, who had probably counseled an unyielding resistance to the foe, in the steadfast faith that Jehovah would help His own; and who, prophet though he was and endowed with miraculous powers, had yet brought no help in this hour of urgent need. (Compare this with the oath of Jezebel against Elijah, 1 Kings 19:2.)