Rashi on Deuteronomy 25:15/רש"י על דברים כ״ה:ט״ו

1אבן 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).