Cal. Civ. Code § 1803.10

It shall be unlawful for any seller to induce or attempt to induce any person to enter into a contract subject to this act by offering a rebate, discount, commission, or other consideration, contingent upon the happening of a future event, on the condition that the buyer either sells, or gives information or assistance for the purpose of leading to a sale by the seller of, the same or related goods.