Is money acquired from selling a product that did not conform to the specifications declared on its label considered permissible (halal), knowing that the product was of acceptable or high quality in some cases, and that non-conforming products were replaced for those who discovered the discrepancy?

Deception and fraud are forbidden by Islamic law. It is narrated from Abu Hurairah that the Messenger of Allah, peace and blessings be upon him, said: "Whoever cheats is not from me." One form of fraud is for the seller to mislead the buyer into believing that a desired quality exists in the sold item when it does not, or to conceal the absence of an existing desired quality. If this occurs, and the sold item has not been consumed or transformed, the item must be returned. If it has been consumed or transformed, the seller must return the difference between the value of the fraudulent item and the value of a sound item. An example of this is if someone sells a fraudulent item for ten (units of currency), and its value if it were sound would be ten, but due to the defect, its value is eight. In this case, two (units of currency) should be returned to the buyer. If returning it is not possible, it should be given as charity on his behalf. This applies if the buyer was unaware of the fraud and did not consent to it.