If, however, you fail to obey Me and to carry out all these commandments,
14. But if ye will not hearken unto me. Thus far a kind invitation has been set before the people in the shape of promises, in order that the observance of the Law might be rendered pleasant and agreeable; since, as we have already seen, our obedience is then only approved by God when we obey willingly.
After God had set the blessing before them (the life and good which would make them a happy people if they would be obedient), he here sets the curse before them, the death and evil which would make them as miserable if they were disobedient.
Commenting on Leviticus 26:14-39
And if ye shall despise my statutes,.... Which is an aggravated sin; to be negligent hearers of the commands of God is bad, not to be doers of them worse, but to treat them with contempt is worse still: or if your soul abhor my judgments: which is worst of all, to despise them as if not wisely or righteously made is a dreadful reflection...