And may be changed to “But,” as in New Jewish Publication Society’s Tanakh, since Moses is now responding to what Yahweh has said. One may say “But Moses answered.” The people cannot come up to Mount Sinai is literally “The people are not able to ascend unto Mount Sinai.” New Revised Standard Version has “The people are not permitted to come up.” Since Mount Sinai is already understood, Good News Translation omits it as unnecessary.

For thou thyself didst charge us refers back to verse 12. The word for charge is the same word for “warn” in verse 21, so New Revised Standard Version and others have “you yourself warned us.” Good News Translation has “you commanded us.” Saying introduces the words of Yahweh as a quote within a quote.

Set bounds about the mountain is literally “you [singular] delimit the mountain,” which in verse 12 was “you will delimit the people.” (See the comment there.) And consecrate it is literally “and you will make it holy,” or “consider it holy,” or “keep it holy.” It is not clear whether the mountain was made holy by means of setting the boundary, or whether the boundary simply marked it off as already holy. New Revised Standard Version seems to favor the latter: “Set limits around the mountain and keep it holy.” Good News Translation interchanges the two clauses in order to give it the same meaning: “to consider the mountain sacred and to mark a boundary around it.” (Note that Good News Translation changes the embedded quote to an indirect statement.) Translators may use the idea of “taboo” in this context; for example, “Consider the mountain taboo.” (See the comment on “taboo” at verse 12.)

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 .