III. God by the prophet sends them a gracious message for their support and comfort under their affliction. The preface to this message is both awful and encouraging (v. 17): Thus saith Jehovah, the eternal God, thy Redeemer, that has often been so, that has engaged to be so, and will be faithful to the engagement, for he is the Holy One, that cannot deceive, the Holy One of Israel, that will not deceive them. The same words that introduce the law, and give authority to that, introduce the promise, and give validity to that: "I am the Lord thy God, whom thou mayest depend upon as in relation to thee and in covenant with thee."