Is it permissible to fulfill a vow with money other than that originally designated for it, after the originally vowed money has been disposed of?

A vow of obedience must be fulfilled, for the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him." A vow contingent on a condition is disliked, but it must be fulfilled if the condition occurs. If the vow is specified from a particular reward, it is safer to fulfill it from that reward. If the reward has been spent, it is obligatory to fulfill it from other wealth. Prompt fulfillment is obligatory, and delay is not permissible.