Reference: http://www.alfawzan.af.org.sa/node/2367
Question: And also, his father does not pray, and when he advises him, he says: I know more than you. So what do you advise he does?
Response: You mean he does not know about salaah?! His father [says he] knows more than him, and [yet he] does not know about salaah?!
He has not attained [knowledge], [rather], he has become a compound ignoramus – and refuge is sought in Allaah; [Either that], or he is a savant of misguidance.
So, [despite the calamity of the situation], he is [still] required to maintain sincere advice to his father, and [remind him of] Allaah’s punishment; [Yes] he [should remind him of] Allaah ‘Azza wa Jall’s punishment. If his father refuses, and [if] he is able to separate from him, then he should move out and live away from him, in a house with his [own] family, or [even] live by himself.
Yet [throughout], he must maintain his duty, honour and kindness towards his father, even if he is living [separately] in another house; Yes.
كيفية نصيحة الولد لوالده التارك للصلاة
المرجع: http://www.alfawzan.af.org.sa/node/2367
السؤال: و أيضًا والده لا يصلي و يقول: عندما أنصحه يقول: أنا أعرف أكثر منك ، فما تنصحونني أن أعمل معه ؟
الجواب: يعني و لا عرف الصلاة ؟ هو يعرف أكثر منه و لا يعرف الصلاة ؟ هذا ما صار، هذا صار جهلٌ مركب – و العياذ بالله – أو إنه عالم ضلال، فعليه إنه يواصل النصيحة معه و يُخوِّفه بالله، يخوفه بالله -عزَّ و جلَّ- فإن أبى و هو يقدر أنه ينعزل عنه، ينعزل عنه، يسكن لحاله، في بيت لحاله هو و عياله، أو هو يسكن ببيت لحاله، لكن يواصل معه البر و الإحسان و لو كان ساكنًا في بيتٍ آخر، نعم.