The statement of the object of the institution, or the application of the property left by the testator, or the charge imposed by him, shall not be considered as a condition unless it appears that such was his intention.
That which has been left in this manner may be claimed at once provided that the instituted heir or his heirs give security for compliance with the wishes of the testator and for the return of anything he or they may receive, together with its fruits and interests, if he or they should disregard this obligation. (797a)