Messenger of Allah ﷺ said thrice, "Shall I not inform you of the biggest of the great sins?" We said, "Yes, O Messenger of Allah ﷺ" He said, "To join partners in worship with Allah: to be undutiful to one's parents." The Prophet ﷺ sat up after he had been reclining and added, "And I warn you against giving forged statement and a false witness; I warn you against giving a forged statement and a false witness." The Prophet kept on saying that warning till we thought that he would not stop.
قَالَ رَسُولُ اللَّهِ ﷺ أَلاَ أُنَبِّئُكُمْ بِأَكْبَرِ الْكَبَائِرِ قُلْنَا بَلَى يَا رَسُولَ اللَّهِ قَالَ الإِشْرَاكُ بِاللَّهِ وَعُقُوقُ الْوَالِدَيْنِ وَكَانَ مُتَّكِئًا فَجَلَسَ فَقَالَ أَلاَ وَقَوْلُ الزُّورِ وَشَهَادَةُ الزُّورِ أَلاَ وَقَوْلُ الزُّورِ وَشَهَادَةُ الزُّورِ فَمَا زَالَ يَقُولُهَا حَتَّى قُلْتُ لاَ يَسْكُتُ