What is the ruling on selling a commercial store for a larger amount than its owner was informed, while giving him the amount he requested and keeping the remainder?

If a person is entrusted with selling a commodity for a fixed or unspecified price, it is not permissible to lie about the price; because it is deception and consuming wealth unjustly, and the increase belongs to the owner of the shop unless he willingly relinquishes it. However, if the owner says, "Sell it for such-and-such, and whatever is extra is yours," then this is permissible, and the increase belongs to the agent. And there is nothing wrong with him saying: "Sell this garment, and whatever exceeds such-and-such is yours."