This emphatic reproduction of the old rule of Deuteronomy 25:13-14 is perhaps a trace of the danger of dishonesty incidental to the growing commerce of the Israelites. The stress laid upon the same sin in Proverbs 16:11; Proverbs 20:10; bears witness to the desire of the teacher to educate the youth of Israel to a high standard of integrity, just as the protest of Hosea against it Hosea 12:7 shows the zeal of the prophet in rebuking what was becoming more and more a besetting sin.
A just weight - literally, as in the margin, indicating a time when stones rather than metal were used as a standard of weight. Compare Deuteronomy 25:13.