What is the ruling on the Udhiyah (sacrificial animal) bought by the father with the grandmother's money, even though the father is able to purchase it with his own money?

If the grandmother permits the father to take the money for purchasing the sacrificial animal (udhiyah), then there is no problem. However, if he takes it wrongfully, he has disobeyed Allah and must repent and return the money. Nevertheless, his sacrifice is valid.