991. Every obligation must have for its subject something to be given, to be done, or not to be done.
992. An obligation must have for its subject something determinate at least as to its kind.
The quantity may be uncertain, provided it is capable of being ascertained.
993. Future things may be the subject of an obligation.
But a person cannot, except in a marriage contract, renounce a succession not yet devolved, nor make any stipulation with regard to it, even with the consent of him or her whose succession is in question.
994. The subject of an obligation must be something possible and not forbidden by law or good morals.