Matthew 6:12

And forgive us our debts--A vitally important view of sin, this--as an offense against God demanding reparation to His dishonored claims upon our absolute subjection. As the debtor in the creditor's hand, so is the sinner in the hands of God. This idea of sin had indeed come up before in this discourse--in the warning to agree with our adversary quickly, in case of sentence being passed upon us, adjudging us to payment of the last farthing, and to imprisonment till then (Mat 5:25-26). And it comes up once and again in our Lord's subsequent teaching--as in the parable of the creditor and his two debtors (Luk 7:41, &c.), and in the parable of the unmerciful debtor (Mat 18:23, &c.). But by embodying it in this brief model of acceptable prayer, and as the first of three petitions more or less bearing upon sin, our Lord teaches us, in the most emphatic manner conceivable, to regard this view of sin as the primary and fundamental one.

— Jamieson-Fausset-Brown Commentary (public domain)