Forgive us our trespasses as we forgive those who trespass against us

We made the humble request for daily bread - that our needs alone (not our wants) for this day alone (not for tomorrow) would be provided by God - and now we make a second request. And this one is likewise humbly done.

Forgive us our sins is something God must do, as noted in the New Testament when Jesus forgave the sins of many (see Matthew 9:2-6; Mark 2:5-10; Luke 5:20-24; 7:41-49) while onlookers were surprised due to the fact that they understood that only God could forgive sins. This element of the Lord's Prayer is extremely critical, as unforgiven sin is a barrier between us and God. Repentance and forgiveness allows prayer to be heard.

But notice the qualifier in this request for forgiveness. Forgive us our trespasses as we forgive those who trespass against us. We cannot expect to be forgiven if we are not willing to forgive. And this is often hard to do. Nevertheless, it has been said many times that Christians ought to be the most forgiving people since we have understood our sin and the forgiveness that we are granted in Christ. How many times ought we forgive? As many times as forgiveness is requested of us. And we certainly want this level of forgiveness from our Heavenly Father, as we, though justified, remain sinners as we battle through the evils of this world.

In Matthew 6, where Jesus teaches the Lord's Prayer, He concludes with these words (v14-15):
"For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins." Forgiveness is a serious matter. Repent and receive the grace of forgiveness - as you forgive others.