Isaiah 38:17

for peace--instead of the prosperity which I had previously. great bitterness--literally, "bitterness to me, bitterness"; expressing intense emotion. in love--literally, "attachment," such as joins one to another tenderly; "Thou hast been lovingly attached to me from the pit"; pregnant phrase for, Thy love has gone down to the pit, and drawn me out from it. The "pit" is here simply death, in Hezekiah's sense; realized in its fulness only in reference to the soul's redemption from hell by Jesus Christ (Isa 61:1), who went down to the pit for that purpose Himself (Psa 88:4-6; Zac 9:11-12; Heb 13:20). "Sin" and sickness are connected (Psa 103:3; compare Isa 53:4, with Mat 8:17; Mat 9:5-6), especially under the Old Testament dispensation of temporal sanctions; but even now, sickness, though not invariably arising from sin in individuals, is connected with it in the general moral view. cast . . . behind back--consigned my sins to oblivion. The same phrase occurs (Kg1 14:9; Neh 9:26; Psa 50:17). Contrast Psa 90:8, "Thou hast set our iniquities before thee, our secret sins in the light of thy countenance."

— Jamieson-Fausset-Brown Commentary (public domain)