If Christ, then, is to be our fear, that is, when He should be worshiped by us, it is necessary that we have the Word and promise of God. Such fear or dread is true worship, which brings it to pass in us that we despise all other dread and terrors, as Isaiah says (8:12–13): “Do not fear what they fear, nor be in dread. But the Lord you shall regard as holy.” He will protect you well, and you must consider that He is to be feared, revered, and worshiped, who speaks with you. “If you do this, then I the Lord will be your fear,” He says. For you have a certain and firm Word, and when you retain it, you will not err in your divine worship.
Luther’s works, vol. 6: Lectures on Genesis: Chapters 31-37 p 85-86