Rashi on Deuteronomy
אבן שלמה וצדק יהיה לך THOU SHALT HAVE A PERFECT AND JUST WEIGHT — This again suggests: if you will do this, (using just weights and measures), you will have (יהיה לך) much (cf. Sifrei Devarim 294:3).
Rashbam on Deuteronomy
שלמה וצדק, one single chunk, (not composites) true and fair.
Rabbeinu Bahya
אבן שלמה וצדק יהיה לך, “a perfect and honest weight you shall have.” If you make sure to have honest weights, and your business will be based on fairness you will have alot, i.e. יהיה לך [as opposed to the previous לא יהיה לך, Ed.].