For I am the Lord, I change not— "Because I am the same yesterday, to-day, and for ever, and am true to the promises given to your fathers, therefore you still continue a people, and are not consumed as your iniquities deserve." See Lowth and Calmet.
Related Commentaries of Malachi 3:6
Malachi 3:6
6 For I am the LORD, I change not; therefore ye sons of Jacob are not consumed.