When Ephraim saw his sickness, and Judah saw his wound, then went Ephraim to the Assyrian, and sent to king Jareb: yet could he not heal you, nor cure you of your wound.
When Ephraim saw his sickness, and Judah saw his wound - literally, bandage: hence, a bandage wound (Isaiah 1:6, "From the sole of the foot even unto the head there is no soundness in it; but wounds, and bruises, and putrifying sores;" Jeremiah 30:12). As the "sickness" refers to the gradual inward decay, so the "wound" refers to the judicial stroke from without, inflicted by God through the hands of enemies. "Saw" - felt its weakened state politically, and the dangers that threatened it. It aggravates their perversity that, though sensible of their unsound and calamitous state, they did not inquire into the cause, or seek a right remedy.
Then went Ephraim to the Assyrian - first, Menahem (2 Kings 15:19) applied to Pul, giving "a thousand talents of silver, that his hand might be with him to confirm the kingdom in his hand;" again Hoshea to Shalmaneser (2 Kings 17:3).
And sent to king Jareb. Understand Judah as the nominative to "sent," Thus, as "Ephraim saw his sickness" (the first clause) answers in the parallelism to "Ephraim went to the Assyrian" (the third clause), so "Judah saw his wound" (the second clause) answers to (Judah) "sent to king Jareb" (the fourth clause). Jareb ought rather to be translated, 'their defender,' literally; avenger (Jerome). The Assyrian "king," ever ready, for his own aggrandizement, to mix himself up with the affairs of neighbouring states, professed to undertake Israel's and Judah's cause: in Judges 6:32, Jerub, in Jerubbaal, is so used-namely, 'plead one's cause.' Judah, under Ahaz, applied to Tiglath-pileser for aid against Syria and Israel (2 Kings 16:7-8; 2 Chronicles 28:16-21): the Assyrian "distressed him, but strengthened him not," fulfilling the prophecy here, "He could not heal you, nor cure you of your wound." Thinking to get the Assyrian as an helper against God's judgments for sin, Israel found the expected helper to be God's 'avenger,' leading him into captivity as a deserter from God.