Matthew 5:23 Therefore if you bring your gift to the altar, and there remember that your brother has something against you,
What is your attitude toward doing things for God? Or for giving things to God?
We may well straighten out our prayer life and start praying with the right attitude, but unless we are doing the same in our lives we are fooling ourselves only.
God wants us to be good examples for Him; people who can give a good account of Christ through their actions as well as through their words.
If you have anything against anyone, try straighten it out before it brings you down as well.