Is it permissible to buy goods from the workplace at the advertised retail price, then sell them to other customers on credit with a small profit, knowing that potential losses from some customers' failure to pay would be borne?

First: The employee is a private hire, and his services are owned by his employer during working hours. He is not permitted to work for his own benefit or for anyone other than his employer without permission.

Second: It is permissible to buy fish from the workplace and sell it outside working hours, provided that you are not responsible for the sale. If you are, then it is not permissible to sell to yourself unless there is explicit or customary permission. It is permissible to sell what you have purchased to others after working hours, while being careful not to divert the shop's customers from buying from it.

Third: The worker is not responsible for the delay of debtors unless it is due to his own negligence, based on the Prophet's (PBUH) saying: "There is no guarantee upon one entrusted." He is a trustee and does not guarantee the damage of money unless there is dereliction of duty on his part.