Abu Bakrah reported: The Prophet, peace and blessings be upon him, said three times, “Shall I not tell you about the worst of major sins?” They said, “Of course, O Messenger of Allah.” The Prophet said, “They are to associate partners with Allah and to be disrespectful to parents.” The Prophet was reclining and he sat up, saying, “And surely to speak falsely.” The Prophet continued to repeat it until we wished he had stopped.
Source: Ṣaḥīḥ al-Bukhārī 2511, Ṣaḥīḥ Muslim 87
Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim
عَنْ أَبِي بَكْرَةَ قَالَ قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَلَا أُنَبِّئُكُمْ بِأَكْبَرِ الْكَبَائِرِ ثَلَاثًا قَالُوا بَلَى يَا رَسُولَ اللَّهِ قَالَ الْإِشْرَاكُ بِاللَّهِ وَعُقُوقُ الْوَالِدَيْنِ وَجَلَسَ وَكَانَ مُتَّكِئًا فَقَالَ أَلَا وَقَوْلُ الزُّورِ قَالَ فَمَا زَالَ يُكَرِّرُهَا حَتَّى قُلْنَا لَيْتَهُ سَكَتَ
2511 صحيح البخاري كتاب الشهادات باب ما قيل في شهادة الزور
87 صحيح مسلم كتاب الإيمان باب بيان الكبائر وأكبرها