en_tn/isa/38/17.md

from the pit of destruction

Hezekiah did not die but he was close to dying. This refers Yahweh saving him from dying. The full meaning of this statement can be made clear. Alternate translation: "from dying and going to the pit of destruction" or "so that I did not die" (See: rc://en/ta/man/jit/figs-explicit)

for you have thrown all my sins behind your back

Hezekiah speaks of Yahweh forgiving his sins as if they were objects that Yahweh threw behind himself and forgot about. Alternate translation: "for you have forgiven all my sins and no longer think about them" (See: rc://en/ta/man/jit/figs-metaphor)