كتاب الإيمان
1
The Book of Faith
(38)
Chapter: The major sins and the most serious of them
(38)
باب بَيَانِ الْكَبَائِرِ وَأَكْبَرِهَا ‏‏
Sahih Muslim 90 a

It is narrated on the authority of 'Abdullah b. Amr b. al-'As that the Messenger of Allah (ﷺ) observed:

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.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا اللَّيْثُ، عَنِ ابْنِ الْهَادِ، عَنْ سَعْدِ بْنِ إِبْرَاهِيمَ، عَنْ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرِو بْنِ الْعَاصِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم 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 ‏"‏ ‏.‏
Reference : Sahih Muslim 90 a
In-book reference : Book 1, Hadith 169
USC-MSA web (English) reference : Book 1, Hadith 162
  (deprecated numbering scheme)