How should a young man act who took 400 pounds from his father under the pretext of private lessons, then spent it on indecent magazines, and has repented, knowing that he cannot deduct the amount from his allowance?

A son taking his father's money and spending it on matters his father dislikes is considered an transgression and injustice, and he incurs sin for his action. The wealth of a Muslim is not permissible for his brother unless it is given with good will from him. The son must return these funds to his father whenever he is able, or seek his father's forgiveness by informing him of what he has done and asking for his pardon. He should not inform him about purchasing disreputable magazines, as that is a sin, and he must conceal himself with Allah's concealment and repent with sincere repentance.