What is my duty towards those who bought a product from me, which I was later informed might be counterfeit after I had sold it, and what is the ruling on selling or using the remaining quantity I have of it, and what should I do regarding the manufacturing company?

The rights concerning the infringement of original trademarks are established as a liability upon whoever adulterates the product and manufactures it without the permission of its owners. As for the product itself, it is permissible property. Whoever owns it through legitimate means and does not adulterate it, is allowed to benefit from it and sell it, provided its condition is clarified. If one is not certain that the product is counterfeit, the original state is that of innocence, and a person's liability is not engaged except by a verified matter or a dominant presumption. Therefore, the original state is the innocence of people's liabilities until the reasons for obligation are established.