All they that had separated themselves. — If these meant proselytes from heathenism, this verse would be a perfect description of the constituents of the people. But we have no record as yet of a recognised body of such proselytes; and the word “separated” is the same as we find, with another meaning, in Nehemiah 9:2. Moreover, the following verses show that the covenant bears specially in mind the danger to God’s law arising out of commerce with the heathen.
Having understanding. — Children who could intelligently take the oath were included.