Deuteronomy 6:14

14.Ye shall not go after. In this passage Moses commands the people not to turn away from the simple service of God, although examples of superstition may present themselves to their sight on every side. For this was a very destructive temptation, that none could be anywhere found who subscribed to the doctrine of the Law, although the respective nations had some religion, or at any rate the name of it existing among them. Since, therefore, these various forms of worship were so many temptations to forsake the right way, it was needful to provide against the danger betimes, and so to establish the authority of the One God, that the Jews might have courage to despise the common belief of all the Gentiles. A threat is added, that vengeance would not be far off if they should fall away into these superstitions, since God is a jealous God, and dwelling among them. As to the former epithet, I am about to say more under the Second Commandment. Meanwhile, let my readers observe that God is called jealous, because He permits no rivalry which may detract from His glory, nor does He suffer the service which is due to Him alone to be transferred elsewhere. When He reminds the people that he dwells among them, it is partly to inspire terror by reason of His presence, and partly to reprove indirectly their ingratitude, if they should forsake Him, and seek for themselves gods who are afar of.