What is the ruling on a father preventing his son from voluntary fasting and from giving charity from his own money that the father gives him?

If lust overwhelms you and you fear falling into the forbidden (haram), then you are not obliged to obey your father in leaving the fast; because there is no obedience to a creature in disobedience to the Creator. However, if lust is not like that, or if your father does not object to your marriage, then obedience to him is obligatory. It is best not to disobey him openly, and if fasting or charity is necessary, then do it secretly; so that you combine obedience to him with righteous deeds without harming him.