[ULPIANUS libro trigensimo ad edictum. ] §18.3.3.prNam legem commissoriam, quae in uenditionibus adicitur, si uolet uenditor exercebit, non etiam inuitus.
[ULPIANUS, On the Edict, book 30.] the forfeiture clause, which is added in sales, the seller will enforce if he wishes, but not also against his will.