Ixsaan to the parents is obligatory

[cunug3aad]

وَقَضَىٰ رَبُّكَ أَلَّا تَعْبُدُوٓا۟ إِلَّآ إِيَّاهُ وَبِٱلْوَٰلِدَيْنِ إِحْسَـٰنًا ۚ إِمَّا يَبْلُغَنَّ عِندَكَ ٱلْكِبَرَ أَحَدُهُمَآ أَوْ كِلَاهُمَا فَلَا تَقُل لَّهُمَآ أُفٍّۢ وَلَا تَنْهَرْهُمَا وَقُل لَّهُمَا قَوْلًۭا كَرِيمًۭا وَٱخْفِضْ لَهُمَا جَنَاحَ ٱلذُّلِّ مِنَ ٱلرَّحْمَةِ وَقُل رَّبِّ ٱرْحَمْهُمَا كَمَا رَبَّيَانِى صَغِيرًۭا​

"And your Lord has decreed that you do not worship except Him, and to parents ixsaan. Whether one or both of them reach old age [while] with you, say not to them [even] "uff," and do not repel them and speak to them a noble word, and lower to them the wing of humility out of mercy and say, "My Lord, have mercy upon them as they brought me up [when I was] small.""

 

[cunug3aad]

Ixsaan is put on the same level of decree as worship of Allaah, and even if your parents are ill fit to parent you should still speak respectfully to them, Example ibraahiim

قَالَ أَرَاغِبٌ أَنتَ عَنْ ءَالِهَتِى يَـٰٓإِبْرَٰهِيمُ ۖ لَئِن لَّمْ تَنتَهِ لَأَرْجُمَنَّكَ ۖ وَٱهْجُرْنِى مَلِيًّۭا قَالَ سَلَـٰمٌ عَلَيْكَ ۖ سَأَسْتَغْفِرُ لَكَ رَبِّىٓ ۖ إِنَّهُۥ كَانَ بِى حَفِيًّۭا​

[His father] said, "Have you no desire for my gods, O Abraham? If you do not desist, I will surely stone you, so avoid me a prolonged time." [Abraham] said, "Peace [i.e., safety] will be upon you. I will ask forgiveness for you of my Lord. Indeed, He is ever gracious to me.