וּמִכַּ֤ף מֶֽלֶךְ־אַשּׁוּר֙ אַצִּ֣ילְךָ֔ וְאֵ֖ת הָעִ֣יר הַזֹּ֑את וְגַנּוֹתִ֖י עַל־הָעִ֥יר הַזֹּֽאת׃
我要救你和這城脫離亞述王的手，我也要保護這城。
Rashi
And from the hand of the king of Assyria will I save you We deduce that he became ill before the downfall of Sennacherib.