Mark 11:24-26 (KJV)
24 Therefore I say unto you, What things soever ye desire, when ye pray, believe that ye receive them, and ye shall have them.
25 And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses.
26 But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses.
Prayer requires us to forgive others and also asking forgiveness for our own sins.  “Matthew 6:12 (KJV) And forgive us our debts, as we forgive our debtors.”. Then we can be confident as we pray according to the will of GOD that we will be heard and receive the answer “1 John 5:14 (KJV) And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us:”.
In Mark 11:25-26 we see that forgiving others, what they have done or not done to us is essential. Jesus Himself prayed on the cross “Luke 23:34 (KJV) Then said Jesus, Father, forgive them; for they know not what they do. And they parted his raiment, and cast lots.”. Who are we to hold a grudge and not forgive? How can we being forgiven of our sins not forgive as well? Un-forgiveness, hurts us the most by not being able to move on, being in bondage and in the end loosing our forgiveness. Jesus told a parable about this. 
“Matthew 18:21-35 (KJV) Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times? 22 Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven. 23 Therefore is the kingdom of heaven likened unto a certain king, which would take account of his servants. 24 And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents. 25 But forasmuch as he had not to pay, his lord commanded him to be sold, and his wife, and children, and all that he had, and payment to be made. 26 The servant therefore fell down, and worshipped him, saying, Lord, have patience with me, and I will pay thee all. 27 Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt. 28 But the same servant went out, and found one of his fellowservants, which owed him an hundred pence: and he laid hands on him, and took him by the throat, saying, Pay me that thou owest. 29 And his fellowservant fell down at his feet, and besought him, saying, Have patience with me, and I will pay thee all. 30 And he would not: but went and cast him into prison, till he should pay the debt. 31 So when his fellowservants saw what was done, they were very sorry, and came and told unto their lord all that was done. 32 Then his lord, after that he had called him, said unto him, O thou wicked servant, I forgave thee all that debt, because thou desiredst me: 33 Shouldest not thou also have had compassion on thy fellowservant, even as I had pity on thee? 34 And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. 35 So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.”
Let us pray and examine ourself and see if the LORD shows us if we have any un-forgiveness in our hearts asking the LORD to forgive us and to forgive everyone from our heart.

NOTE: Here are some other devotions about forgiveness:
Mercy and judgement – 2024.05.18 https://missioncommunities.network/2024/05/18/mercy-and-judgement-2024-05-18/
Crying out for forgiveness – 2024.05.01 https://missioncommunities.network/2024/05/01/crying-out-for-forgiveness-2024-05-01/
Mercy versus sacrifice – 2024.05.22 https://missioncommunities.network/2024/05/22/mercy-versus-sacrifice-and-repentance-2024-05-22/
Forgiveness needs to be followed by repentance – 2024.04.30 https://missioncommunities.network/2024/04/30/forgiveness-needs-to-be-followed-by-repentance-2024-04-30/