Behold, I make a covenant, i.e. I do hereby renew my covenant with thy people which they had violated and voided by their sin. But the shortness of the phrase, there being no mention here of any with whom this covenant is made or renewed, and the following words, make it more probable that this covenant is nothing but a solemn promise or engagement that God will do the thing which here follows. And the word covenant is oft used for a mere promise, as Genesis 9:9, &c.; Leviticus 24:8 Numbers 18:19, Numbers 25:12. It is a terrible thing that I will do with thee; either,
1. By thy ministry, as that phrase is sometimes used, as 1 Corinthians 15:10. Or,
2. In the midst of thee, i.e. of thy people, as Exodus 34:11, before thee, i.e. before thy people. This I prefer, because the next verse explains this of such things as were not done by Moses's ministry, nor in his time, but afterwards.