Assalamu alaykum.Is it permissible to buy the product of a company from the supervisor/other employee of a company without the company knowing about it?The person says that he is responsible for it and I don't need to be worried?Please advice.Jazak Allah khayr

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Buying the product should be from the owner or his agent, however if the supervisor or the employee does not have the authority to sell the company's products then his act is considered as an interfering. This interfering is not accepted unless the owner gives the permission for that. As for the questioner’s saying “without the knowledge of the company” indicates that the company does not allow this selling, and thus the sale is invalid. If it meant by "without the knowledge of the company " that the supervisor is selling the company's products and taking the money for himself, then it is a theft, and the sale is thus invalid. If the buyer is aware of this act committed by the supervisor, then he is a partner in theft. If this is the case, the supervisor should be advised to repent to Allah, The Exalted, and return the rights to their owners.

Allah knows best.