Testimonies for the Church vol.1 p.121
"I saw that every prayer which is sent up in faith from an honest heart will be heard of God and answered, and the one that sent up the petition will have the blessing when he needs it most, and it will often exceed his expectations. Not a prayer of a true saint is lost if sent up in faith from an honest heart."
The effectual fervent prayer of a righteous man avails much.