Is it permissible to offer expiation for a vow to sacrifice a specific calf if the mother prevents her son from sacrificing it and threatens to be angry with him?

Undertaking a vow (nadhr) is disliked (makruh), but if a Muslim makes a specific vow, it becomes obligatory to fulfill it if it involves obedience to Allah. It is not permissible to change it as long as fulfillment is possible, based on the Prophet's (peace be upon him) saying: "Whoever vows to obey Allah, let him obey Him; and whoever vows to disobey Allah, let him not disobey Him."

Therefore, it is obligatory to slaughter the specific calf mentioned in the vow, and an expiation for an oath (kaffarat yamin) is not sufficient. The mother has no right to demand non-fulfillment of the vow. Rather, it must be explained that fulfilling it is a right owed to Allah, and obedience to Allah takes precedence over obedience to created beings. If the mother is not pleased, it is not permissible to obey her in abandoning the fulfillment of the vow, based on the Prophet's (peace be upon him) saying: "There is no obedience in sin; obedience is only in what is good." Obedience to parents is in matters that do not involve sin, and there is no obedience to a creature in disobeying the Creator.