What is the ruling of Islamic law regarding dealing with a father who insists on costly, non-essential matters for marriage, thereby hindering its completion, and is it permissible for the son to raise his voice at his father when angry?

One must repent for raising one's voice at one's father and addressing him inappropriately. One should seek his رضا (satisfaction) and explain that the action was due to intense anger, and express remorse for it. Then, advise him gently and kindly regarding extravagance in worldly matters. If the father disposes of his son's money in a way the son does not desire, the son should overlook it as an act of piety towards him, for it is hoped that Allah will compensate him.