John Gill Commentary Lamentations 3:42

"We have transgressed and have rebelled; thou hast not pardoned." — Lamentations 3:42 (ASV)

We have transgressed, and have rebelled
Here begins the prayer, the sense of which is directed to, though the words are not dictated; and it begins with confession of sin, as prayer should, especially when in such circumstances as the people of the Jews now were; and with confession of it, as a transgression of the law of God; and as rebellion against him, as every sin is, a breach of his law, a contempt of his authority, and a trampling under foot his legislative power, and an act of hostility against him; and so downright rebellion; every sin being an overt act of that kind; and which is aggravated by the favours before acknowledged to have been received.

: you have not pardoned ;
as they apprehended; they had not the discovery and application of pardoning grace and mercy; otherwise pardon of sin with God is past, and includes all sin present and future, as well as past; but temporal afflictions being upon them, they concluded their sins were not pardoned; pardon of sin in Scripture often signifying the removal of such afflictions.