Let us be merciful as well as just.

Justice settles what is owed, and it can be entirely correct while still being the wrong response. A person can deserve the full consequence and also be someone you would rather not break. Mercy is not a softening of the judgement; it is a separate decision about what to do with a judgement you are entitled to enforce. Having the right to exact something and choosing not to is where most of the character in it sits.

Think of someone who genuinely owes you: an apology, money, an acknowledgement. Decide whether collecting it will improve anything besides the ledger.