The Prayer of Faith
Faith in association with prayer is simply the exercise of confidence in God to do His will in a particular matter. As we pray in the name of Jesus Christ, we are indicating that we have complete confidence that God is going to do what is good for us and that He will never do what is bad for us. Recognizing the sovereignty of God, we are to completely leave all to His jurisdiction as we pray concerning everything, particularly the matter of healing.
— from James the Epistle of Applied Christianity by Theodore Epp.
James 5: 15 and the prayer offered in faith will restore the one who is sick, and the Lord will raise him up, and if he has committed sins, they will be forgiven him. 16 Therefore, confess your sins to one another, and pray for one another so that you may be healed. The effective prayer of a righteous man can accomplish much. 17 Elijah was a man with a nature like ours, and he prayed earnestly that it would not rain, and it did not rain on the earth for three years and six months.