Rashi on Leviticus 25:14/רש"י על ויקרא כ״ה:י״ד

1‎'וכי תמכרו וגו‎‎‎‎ AND IF THOU SELL [OUGHT TO THY FELLOW… YE SHALL NOT OVERREACH ONE ANOTHER] — According to its plain sense the verse intimates what it literally means: (i. e. as translated above). But there is also a Midrashic interpretation: Whence can it be derived that if you sell anything you should sell it to your Israelite fellowman? From what Scripture states: “And if you sell — ,לעמיתך sell it to one associated with you by nationality”. And whence can it be derived that if you intend to buy anything that you should buy it of your Israelite fellow? From what Scripture states “or if thou buy ought — מיד עמיתך, at the hand of one associated with thee, buy it” (Sifra, Behar, Section 3 1).

2אל תונו YE SHALL NOT WRONG [ONE ANOTHER] — This refers to wronging in money matters (Sifra, Behar, Section 3 4).