But when you are praying, first forgive anyone you are holding a grudge against, so that you’re Father in heaven will forgive your sins, too. (Mark 11:25 NLT)
Prayers fail or are unanswered because they lack a very important element, which is the love for God, or faithfulness to God. Obedience to His laws is a requisite for a prayer to be heard. Though we call Him Father, but do not obey His words, He will not recognize us. One of the commands is to forgive. Learn to forgive those who hurt us. If you do not forgive, you will not forget. We should forgive the sinner and forget the sins. A happy man is he who is full of good memories because he forgets all that are bad. A forgiving heart is a loving heart. We love God and express it in our prayers, and we love others and express it by forgiving. It is wrong to say that you are strong by not forgiving for it takes much more courage to forgive and to love somebody who hurt us.
