What is the ruling of the Shari'ah regarding dealing with a father who commits major sins, harms his family, abandons prayer, and demands that his children financially support him? Is not seeking forgiveness for him considered disobedience ( 'uqooq), especially since he performs acts that expel him from the fold of Islam?

The legal stance regarding the father you describe can be summarized as follows:

1. The Obligation of Righteousness: One must be righteous towards their father, no matter what his condition, even if he is immoral or an disbeliever, except in matters of disobedience [to Allah]. This is affirmed by Allah's saying: "But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness." [Luqman: 15].

2. Inviting the Father with Wisdom: Be keen to invite him to Allah with wisdom and good counsel, following the example of Ibrahim (peace be upon him) in his invitation to his father.

3. Praying for His Guidance: Strive to pray for his guidance, choosing times when prayers are likely to be answered, for supplication has a great effect in guiding those who turn away.

4. Seeking Forgiveness for Him: It is permissible to seek forgiveness for the father as long as he is alive, even if he is immoral or an disbeliever, hoping for his faith. However, it is not permissible to seek forgiveness for him after his death upon disbelief, based on Allah's saying: "It is not for the Prophet and those who have believed to ask forgiveness for polytheists, even if they were relatives, after it has become clear to them that they are companions of Hellfire." [At-Tawbah: 113].

5. Denouncing Evil: Denounce the evil emanating from him with gentleness and politeness, for denouncing evil is not waived just because the perpetrator is a parent.

6. Providing for Him: If the father is poor and unable to earn a living, or if his work is not suitable for him, his wealthy children are obligated to provide for him. Even if his idleness does not prevent this, it is considered an act of righteousness.