What is Islam's ruling on a man insulting his father, and is a financial penalty obligatory upon him despite his admission of guilt?

Allah Almighty commanded us to be kind and dutiful to our parents, and He made this among the best deeds after performing prayer at its appointed time. He warned against harming or cursing them, for this is considered among the major sins and a form of disobedience ( 'Uquq) that prevents entry into Paradise. Whoever curses their parents must hasten to sincere repentance, increase in seeking forgiveness and performing acts of obedience, and be kind to their parent and seek their forgiveness. Sincere repentance is accepted, and no financial penalty is required, but rather sincerity in repentance and kindness.