What is the ruling of Islamic law regarding a son severing ties with his father for three years and wishing death upon him?

What the questioner is doing by abandoning his father, cutting ties with him, and treating him poorly is a grave sin and an act of disobedience to parents, which is considered one of the causes for entering Hellfire. The mentioned problems or the father's disobedience do not justify this behavior, for Allah Almighty commanded kindness and benevolence towards them, even if they strive to make their child associate partners with Allah. Scholars have even considered not standing up for parents or frowning at them as acts of disobedience. The questioner must apologize to his father, kiss his hand, ask for his forgiveness, pray for him, and repent to Allah.