Is it permissible for a son to take money in excess of what was agreed upon with his father, who has become less attentive to him and started spending on his new wife, by selling his father's goods at a higher price and keeping the difference without his father's knowledge?

It is not permissible for a son to sell something at a price higher than what was agreed upon with his father, so that he may take the excess for himself without the father's consent. If the wage is not sufficient for him, he has the right to leave work with his father and work elsewhere. The son must honor his father and obey him in what is good, regardless of the father's condition.