Is a son's taking money from his father without his knowledge, after the father refused to give it to him except after great difficulty, considered an act of disobedience, especially since the father later becomes aware of it and does not object?

Good conduct towards one's father and his contentment are a religious obligation. Raising one's voice at him, becoming agitated, or stealing his money are religiously forbidden. Ibn al-Salah (definition) said: "The forbidden disobedience is every act that harms the parent."

Repentance is obligatory, as is seeking the father's forgiveness for the money taken. If he does not forgive, it is obligatory to return it, unless the father was negligent in providing the obligatory maintenance, in which case it is permissible to take from his money an amount sufficient for one's needs.