For thou shall worship no other god,.... Than the Lord their God, the one only living and true God, which was the first command given to the people of Israel, and binding upon all men:
for the Lord whose name is Jealous, is a jealous God; his name and nature answer to one another; he admits of no rival or competitor in worship; he will not give his glory to another god, or one so called, nor his praise to graven images; and in this he is distinguished from all nominal and fictitious gods, who have many joined with them, and are rivals of them, which gives them no concern, because insensible; but it is otherwise with the Lord, who knows the dishonour done him, and resents it, and is as jealous of any worship being given to another, as the husband is of the honour of his marriage bed; for idolatry is spiritual adultery, as is suggested in the following verse.