Article 290 of Commercial Code

1 - If the commission agent for sale grants the purchaser time to pay the price or allows him to pay it in instalments without the principal's permission, the principal may demand that the agent pay the entire price immediately, and in this case the agent may keep the difference if he concludes the transaction at a higher price. 2 - Nevertheless, the commission agent may grant time or allow payment of the price in instalments without the principal's permission if custom in the locality where the sale took place so provides, unless the principal's instructions oblige him to sell for an immediately payable price.