What should a woman who vowed to sacrifice a goat, then sold it while it was young, do with the money she obtained from the sale?

The vow of obedience, including sacrifice, must be fulfilled, for the Prophet, peace and blessings be upon him, said: “Whoever vows to obey Allah, let him obey Him.” The Prophet, peace and blessings be upon him, commanded the fulfillment of the vow of sacrifice.

If the vowed animal is specified by the person, it becomes binding as specified. If he disposes of it, he is liable to guarantee its equivalent or something better. Therefore, you must buy goats equal to the number of heads you vowed and slaughter them, because the vow removes the ownership of the one who vowed and transfers it to the needy, and it is not permissible to dispose of it by selling or gifting.