Leviticus 20:8

i.e. Who separated you from all nations, and from their impurities and idolatries, to be a peculiar people to myself, and therefore I will not suffer you to follow their examples. Or, who really sanctify you, and give you my grace to do what I require, i.e. to keep my statutes. Or the argument is this, Those idols and idolatries will defile you and make you worse, but I only and my service will sanctify you and make you better.