This verse sounds like the conclusion to a long list of instructions, and Moffatt places it after verse 19 for that reason. But we must assume that the editors had some purpose in placing it here. As in verse 9, the second person singular changes to plural.

Take heed, literally “guard yourselves,” means “be careful,” or “be attentive” (New Revised Standard Version). Contemporary English Version has “Make certain you obey everything I have said.” To all that I have said to you refers to all that Yahweh has said, so Good News Translation makes this clear: “Listen to everything that I, the LORD, have said to you.” And make no mention of the names of other gods is literally “and the name [singular] of other gods you [plural] will not cause to be remembered.” This probably means “Do not invoke the names of other gods” (New International Version), and Good News Translation and Contemporary English Version have “Don’t pray to other gods.”

Nor let such be heard out of your mouth is literally “it shall not be heard upon your [singular] mouth.” The “it” is singular because names is singular in the Hebrew, but this is not natural in English. So New Revised Standard Version has “do not let them be heard on your lips.” Note that the your in your mouth suddenly changes back to singular, but the plural should be used in translation if it is more natural. Good News Translation has “do not even mention their names” (similarly Contemporary English Version).

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .