Whether all vows are binding?

Objections

Objection 1 : It would seem that vows are not all binding. For man needs things that are done by another, more than God does, since He has no need for our goods (Ps. 15:2). Now according to the prescription of human laws [*Dig. L. xii, de pollicitat., i] a simple promise made to a man is not binding; and this seems to be prescribed on account of the changeableness of the human will. Much less binding therefore is a simple promise made to God, which we call a vow.
Objection 2 : Further, no one is bound to do what is impossible. Now sometimes that which a man has vowed becomes impossible to him, either because it depends on another's decision, as when, for instance, a man vows to enter a monastery, the monks of which refuse to receive him: or on account of some defect arising, for instance when a woman vows virginity, and afterwards is deflowered; or when a man vows to give a sum of money, and afterwards loses it. Therefore a vow is not always binding.
Objection 3 : Further, if a man is bound to pay something, he must do so at once. But a man is not bound to pay his vow at once, especially if it be taken under a condition to be fulfilled in the future. Therefore a vow is not always binding.