ENOfficial
'Abdullah ibn 'Amr said that the Prophet, may Allah bless him and grant him peace, said, "Reviling one's parents is one of the great wrong actions." They asked, "How could he revile them?" He said, "He reviles a man who then in turn reviles his mother and father."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، قَالَ: أَخْبَرَنَا سُفْيَانُ قَالَ: حَدَّثَنِي سَعْدُ بْنُ إِبْرَاهِيمَ، عَنْ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ عَبْدِ اللهِ بْنِ عَمْرٍو قَالَ: قَالَ النَّبِيُّ صلى الله عليه وسلم: مِنَ الْكَبَائِرِ أَنْ يَشْتِمَ الرَّجُلُ وَالِدَيْهِ، فَقَالُوا: كَيْفَ يَشْتِمُ؟ قَالَ: يَشْتِمُ الرَّجُلَ، فَيَشْتُمُ أَبَاهُ وَأُمَّهُ.
sunnah.com