For the source text click/tap here: Bava Metzia 51
To download, click/tap here: PDF
The source for this discussion of ona’ah appears on our daf. In truth, it is not only a question of whether a person can make an agreement to dispense with the rules of the Torah with regard to money matters, but also a more basic question of how to define the law of ona’ah. Some argue that ona’ah has two sides to it. On the one hand there is a question of money, on the other hand there are elements of issur – of forbidden practices – involved, as well.
We explore the dimensions of the prohibition Lev 25:14 :"וְכִֽי־תִמְכְּר֤וּ מִמְכָּר֙ לַעֲמִיתֶ֔ךָ א֥וֹ קָנֹ֖ה מִיַּ֣ד עֲמִיתֶ֑ךָ אַל־תּוֹנ֖וּ אִ֥ישׁ אֶת־אָחִֽיו׃
When you sell property to your neighbor, or buy any from your neighbor, you shall not wrong one another.
As it applies to business practices.