e obligation both of vow and of an oath arises
from something Divine; but in different ways. For the obligation of a
vow arises from the fidelity we owe God, which binds us to fulfil our
promises to Him. On the other hand, the obligation of an oath arises
from the reverence we owe Him which binds us to make true what we
promise in His name. Now every act of infidelity includes an
irreverence, but not conversely, because the infidelity of a subject
to his lord would seem to be the greatest irreverence. Hence a vow by
its very nature is more binding than an oath.

Reply Obj. 1: A vow is not any kind of promise, but a promise made to
God; and to be unfaithful to God is most grievous.

Reply Obj. 2: An oath is added to a vow not because it is more
stable, but because greater stability results from "two immutable
things" [*Heb. 6:18].

Reply Obj. 3: Deliberation of the mind gives a vow its stability, on
the part of the person who takes the vow: but it has a greater cause
of stability on the part of God, to Whom the vow is offered.
_______________________

NINTH ARTICLE [II-II, Q. 89, Art. 9]

Whether Anyone Can Dispense from an Oath?

Objection 1: It would seem that no one can dispense from an oath.
Just as truth is required for a declaratory oath, which is about the
past or the present, so too is it required for a promissory oath,
which is about the future. Now no one can dispense a man from
swearing to the truth about present or past things. Therefore neither
can anyone dispense a man from making truth that which he has
promised by oath to do in the future.

Obj. 2: Further, a promissory oath is used for the benefit of the
person to whom the promise is made. But, apparently, he cannot
release the other from his oath, since it would be contrary to the
reverence of God. Much less therefore can a dispensation from this
oath be granted by anyone.

Obj. 3: Further, any bishop can grant a dispensation from a vow,
except certain vows reserved to the Pope alone, as stated above (Q.
88, A. 12, ad 3). Therefore in like manner, if an oath admits of
dispensation, any bishop can dispense from an oath. And yet seemingly
this is to be against the law [*Caus. XV, qu. 6, can. Auctoritatem,
seqq.: Cap. Si vero, de Jurejurando]. Therefore it would seem that an
oath does not admit of dispensation.

_On the contrary,_ A vow is more binding than an oath, as stated
above (A. 8). But a vow admits of dispensation and therefore an oath