"If I regard iniquity in my heart, The Lord will not hear." (Psalm 66:18, NKJV)
Perhaps one of the reasons we do not see more answers to prayer is that prayers are often made without a consideration of our personal righteousness. For example, we may be praying for God to help us in a particular area and yet we still harbor bitterness towards someone that hurt us. At the conclusion to the model prayer Jesus said, "“For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you do not forgive men their trespasses, neither will your Father forgive your trespasses." (Matthew 6:14-15, NKJV). Daily confession of sin (1 John 1:9) should be accompanied by unconditional forgiveness to those who have harmed us if we expect that sin to be forgiven by God.
Even personal conflicts that do not have a clear offending party need to be dealt with appropriately if we expect to be in communion with God. In His sermon on the mount Jesus admonished, "Therefore if you bring your gift to the altar, and there remember that your brother has something against you, leave your gift there before the altar, and go your way. First be reconciled to your brother, and then come and offer your gift." (Matthew 5:23-24, NKJV) If this principle was practiced on a regular basis we would either have empty churches or churches full of worshiping folks empty of hypocrisy.
Fortunately most people I know that are submissive to the Word of God and responsive to the conviction of the Holy Spirit are quick to forgive and fast to repair broken relationships. Yet there is still a third area in which we can be guilty of harboring iniquity. It is hard to see our own faults. Sometimes we are not consciously aware of our sinfulness. David prayed, "Who can understand his errors? Cleanse me from secret faults. Keep back Your servant also from presumptuous sins; Let them not have dominion over me. Then I shall be blameless, And I shall be innocent of great transgression. Let the words of my mouth and the meditation of my heart Be acceptable in Your sight, O Lord, my strength and my Redeemer." (Psalm 19:12-14, NKJV)
Oh Lord search my heart today.
"Search me, O God, and know my heart; Try me, and know my anxieties; And see if there is any wicked way in me, And lead me in the way everlasting." (Psalm 139:23-24, NKJV)