conveyance or performance there ought to be a separate question and a
separate answer.

19 As has been already observed, no one can validly stipulate for
performance to a person other than himself, for the purpose of this
kind of obligation is to enable persons to acquire for themselves that
whereby they are profited, and a stipulator is not profited if the
conveyance is made to a third person. Hence, if it be wished to make
a stipulation in favour of any such third person, a penalty should be
stipulated for, to be paid, in default of performance of that which is
in reality the object of the contract, to the party who otherwise would
have no interest in such performance; for when one stipulates for a
penalty, it is not his interest in what is the real contract which
is considered, but only the amount to be forfeited to him upon
nonfulfilment of the condition. So that a stipulation for conveyance
to Titius, but made by some one else, is void: but the addition of a
penalty, in the form 'If you do not convey, do you promise to pay me so
many aurei?' makes it good and actionable.

20 But where the promisor stipulates in favour of a third person, having
himself an interest in the performance of the promise, the stipulation
is good. For instance, if a guardian, after beginning to exercise his
tutorial functions, retires from their exercise in favour of his fellow
guardian, taking from him by stipulation security for the due charge of
the ward's property, he has a sufficient interest in the performance
of this promise, because the ward could have sued him in case of
maladministration, and therefore the obligation is binding. So too a
stipulation will be good by which one bargains for delivery to one's
agent, or for payment to one's creditor, for in the latter case one may
be so far interested in the payment that, if it not be made, one will
become liable to a penalty or to having a foreclosure of estates which
one has mortgaged.

21 Conversely, he who promises that another shall do so and so is not
bound unless he promises a penalty in default;

22 and, again, a man cannot validly stipulate that property which will
hereafter be his shall be conveyed to him as soon as it becomes his own.

23 If a stipulator and the promisor mean different things, there is no
contractual obligation, but it is just as if no answer had been made to
the question; for instance, if one stipulates from you for Stichus, and
you think he means Pam