Jabir b. Abdullah (Allah be pleased with them) is reported to have said that Allah's Messenger ﷺ forbade the sale of a heap of dates the weight of which is unknown in accordance with the known weight of dates.
The Prophet ﷺ also taught us to be mindful and aware when engaging in any kind of business transaction, as this will help us avoid any potential disputes or misunderstandings down the line. We should always strive for transparency and clarity when dealing with others, so that everyone involved can benefit from a fair exchange without feeling cheated or taken advantage of.