Is it permissible to give the entire first salary to one's father instead of donating it as charity, given the father's difficult financial situation, numerous debts, and obligations?

Fulfilling this vow is obligatory, based on the Prophet's (peace be upon him) saying: "Whoever vows to obey Allah, let him obey Him," and Allah's Almighty saying: "Then let them complete their rites, and perform their vows," and His saying: "O you who have believed, fulfill [your] contracts." This is a matter of consensus among scholars. One should beware of resembling those whom Allah Almighty and His Messenger have condemned for failing to fulfill vows. If no specific recipient was designated for the vowed amount, there is no harm in giving it to your father if he is burdened by debt.