Ok. So there are other difficult verses. Perhaps this should be in the Top 10. But read it:
14 For if you forgive other people when they sin against you, your heavenly Father will also forgive you. 15 But if you do not forgive others their sins, your Father will not forgive your sins.
What we receive from God we are expected to pass on. And in this case it is forgiveness. Forgiveness is one of the greatest gifts Jesus ever gave because our sins were paid by him on the cross. And it is one of the most important, emphasized several times in Scripture, that we practice.