It usually is true that before we can receive a blessing from God we have to know the promise is in the Bible. This is true of being saved. It is true of the gifts of the Spirit, including speaking in tongues. It is true of Divine healing. Once we know God has given the promise we can choose to believe and then pray until we receive.
The New Testament promises us victory over sin. Once we see such victory is scriptural we can choose to believe, and then pray until we receive.
