The value of our prayers, we can all understand, depends exceedingly on the state of mind in which we offer them. But the point before us is one which receives far less attention than it deserves.
Our prayers must not only be earnest, fervent, sincere, and in the name of Christ. They must contain one more ingredient besides. They must come from a forgiving heart. We have no right to look for mercy, if we are not ready to extend mercy to our brethren. We cannot really feel the sinfulness of the sins we ask to have pardoned if we cherish malice towards our fellow men. We must not flatter ourselves that we have the Spirit of adoption if we cannot bear and forbear.
~ J.C. Ryle
Expository Thoughts on the Gospels: Mark, [Carlisle, PA: Banner of Truth, 1985], 239, 240.