Matthew 6:12 in the Lord's Prayer asks for forgiveness as we forgive others, directly paralleling the conditional warning of Mark 11:26.

Matthew 6:14 states the same condition: forgiving others secures your Father's forgiveness, reinforcing Mark 11:26's warning.

In Matthew 18:35, Jesus uses the same severe warning: failure to forgive from the heart results in divine judgment.

Luke 6:37 promises forgiveness for those who forgive — the positive counterpart to this warning.

Ephesians 4:32 urges forgiveness based on God's forgiveness in Christ — a different angle but same core principle.