Allah the Exalted said:
رياض الصالحينAbū Zakariyyā Muḥyī al-Dīn Yaḥyā ibn Sharaf al-Nawawī٢٦٣ - باب بيان غلظ تحريم شهادة الزور
٢٦٣ - باب بيان غلظ تحريم شهادة الزور
That [has been commanded], and whoever honors the sacred ordinances of Allāh - it is best for him in the sight of his Lord. And permitted to you are the grazing livestock, except what is recited to you.1 So avoid the uncleanliness of idols and avoid false statement,
And He the Exalted said:
وَلَا تَقْفُ مَا لَيْسَ لَكَ بِهِۦ عِلْمٌ ۚ إِنَّ ٱلسَّمْعَ وَٱلْبَصَرَ وَٱلْفُؤَادَ كُلُّ أُو۟لَـٰٓئِكَ كَانَ عَنْهُ مَسْـُٔولًا
And do not pursue1 that of which you have no knowledge. Indeed, the hearing, the sight and the heart - about all those [one] will be questioned.
وقال تَعَالَى:
And He the Exalted said:
مَّا يَلْفِظُ مِن قَوْلٍ إِلَّا لَدَيْهِ رَقِيبٌ عَتِيدٌ
He [i.e., man] utters no word except that with him is an observer prepared [to record].
وقال تَعَالَى:
And He the Exalted said:
وَأَمَّآ إِذَا مَا ٱبْتَلَىٰهُ فَقَدَرَ عَلَيْهِ رِزْقَهُۥ فَيَقُولُ رَبِّىٓ أَهَـٰنَنِ
But when He tries him and restricts his provision, he says, "My Lord has humiliated me."
وقال تَعَالَى:
And He the Exalted said:
وَٱلَّذِينَ لَا يَشْهَدُونَ ٱلزُّورَ وَإِذَا مَرُّوا۟ بِٱللَّغْوِ مَرُّوا۟ كِرَامًا
And [they are] those who do not testify to falsehood, and when they pass near ill speech, they pass by with dignity.
وعن أَبي بَكْرَةَ - ﵁ - قَالَ: قَالَ رسُولُ الله - ﷺ: «ألاَ أُنَبِّئُكُمْ بِأكْبَرِ الكَبَائِرِ؟» قُلْنَا: بَلَى يَا رسولَ اللهِ. قَالَ: «الإشْراكُ باللهِ، وعُقُوقُ الوَالِدَيْنِ» وكَانَ مُتَّكِئًا فَجَلَسَ، فَقَالَ: «ألا وَقَولُ الزُّورِ». فما زال يُكَرِّرُهَا حَتَّى قلنا: لَيْتَهُ سَكَتَ . متفق عَلَيْهِ.
It is related from Abū Bakrah (may Allah be pleased with him) who said: The Messenger of Allah ﷺ said: "Shall I not inform you of the gravest of major sins?" We said: Of course, O Messenger of Allah. He said: "Associating partners with Allah, and disobedience to parents." He had been reclining, but then he sat up and said: "And beware — false speech!" And he kept repeating it until we said: Would that he had fallen silent. Agreed upon.