John Wesley on Deuteronomy 17:2

ln transressing his covenant - That is, in idolatry, as it is explained De 17:3, which is called a transgression of God's covenant made with Israel, both because it is a breach of their faith given to God and of that law which they covenanted to keep; and because it is a dissolution of that matrimonial covenant with God, a renouncing of God and his worship, and a chusing other Gods.