Reconcile before you pray.
Therefore, if you bring your gift to the altar, and there recall that your brother has anything against you, leave your gift there at the altar, go first and be reconciled with your brother, and then come and offer your gift. Settle with your opponent quickly while on the way to court with him. Otherwise your opponent will hand you over to the judge, and the judge will hand you over to the guard, and you will be thrown into prison. Truly, I say to you, you will not be released until you have paid the last penny. Matthew 5:23-26
It can be easy to forget that our relationship with God has a lot to do with our relationship with others. In fact, it is difficult to separate the two. As John says in 1 John 2:9-11: “Anyone who claims to be in the light but hates a brother or sister is still in the darkness. Anyone who loves their brother and sister lives in the light, and there is nothing in them to make them stumble. But anyone who hates a brother or sister is in the darkness and walks around in the darkness. They do not know where they are going, because the darkness has blinded them.” Let us do all we can to live at peace with others so our prayers may be unhindered.
As Paul says in Romans 12:17-19: “Do not repay anyone evil for evil. Be careful to do what is right in the eyes of everyone. If it is possible, as far as it depends on you, live at peace with everyone. Do not take revenge, my dear friends, but leave room for God’s wrath, for it is written: “It is mine to avenge; I will repay,” says the Lord.”