Is it permissible to fulfill a vow in installments if it's not possible to fulfill it all at once?

Delaying the fulfillment of a vow for such a long period is impermissible when one is capable of fulfilling it. Rather, it is obligatory to hasten its fulfillment in the manner the one who made the vow specified. If he is able to give it all at once, then that is what is obligatory. Otherwise, he should give what he can as soon as possible without delay.