John Gill Commentary Deuteronomy 25:14

"Thou shalt not have in thy house diverse measures, a great and a small." — Deuteronomy 25:14 (ASV)

You shall not have in your house divers measures
Or, "an ephah and an ephah"; which was one sort of measure in use with the Jews, and held above a bushel; and is put for all others, which should be alike, and not

a great and a small ;
one to buy with, and another to sell by, as before observed; which would be to cheat both seller and buyer in their turns; see (Amos 8:5) .