Abusing one's parents is one of the major sins. They (the hearers) said: Messenger of Allah, does a man abuse his parents too? He (the Holy Prophet) replied: Yes, one abuses the father of another man, who in turn abuses his father. One abuses his mother and he in turn abuses his (the former's) mother.

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مِنَ الْكَبَائِرِ شَتْمُ الرَّجُلِ وَالِدَيْهِ قَالُوا يَا رَسُولَ اللَّهِ هَلْ يَشْتِمُ الرَّجُلُ وَالِدَيْهِ قَالَ نَعَمْ يَسُبُّ أَبَا الرَّجُلِ فَيَسُبُّ أَبَاهُ وَيَسُبُّ أُمَّهُ فَيَسُبُّ أُمَّهُ