Kuhzayma = Two Witnesses

Some claim that Khuzaymah’s testimony was accepted because it was considered the equivalent of two people. This understanding comes from the following sunnah of Abi Dawud 3607.

Narrated Uncle of Umarah ibn Khuzaymah: The Prophet (ﷺ) bought a horse from a Bedouin. The Prophet (ﷺ) took him with him to pay him the price of his horse. The Messenger of Allah (ﷺ) walked quickly and the Bedouin walked slowly. The people stopped the Bedouin and began to bargain with him for the horse as and they did not know that the Prophet (ﷺ) had bought it. The Bedouin called the Messenger of Allah (ﷺ) saying: If you want this horse, (then buy it), otherwise I shall sell it. The Prophet (ﷺ) stopped when he heard the call of the Bedouin, and said: Have I not bought it from you? The Bedouin said: I swear by Allah, I have not sold it to you. The Prophet (ﷺ) said: Yes, I have bought it from you. The Bedouin began to say: Bring a witness. Khuzaymah ibn Thabit then said: I bear witness that you have bought it. The Prophet (ﷺ) turned to Khuzaymah and said: On what (grounds) do you bear witness? He said: By considering you trustworthy, Messenger of Allah (ﷺ)! The Prophet (ﷺ) made the witness of Khuzaymah equivalent to the witness of two people.

حَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى بْنِ فَارِسٍ، أَنَّ الْحَكَمَ بْنَ نَافِعٍ، حَدَّثَهُمْ أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، عَنْ عُمَارَةَ بْنِ خُزَيْمَةَ، أَنَّ عَمَّهُ، حَدَّثَهُ وَهُوَ، مِنْ أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم أَنَّ النَّبِيَّ صلى الله عليه وسلم ابْتَاعَ فَرَسًا مِنْ أَعْرَابِيٍّ فَاسْتَتْبَعَهُ النَّبِيُّ صلى الله عليه وسلم لِيَقْضِيَهُ ثَمَنَ فَرَسِهِ فَأَسْرَعَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْمَشْىَ وَأَبْطَأَ الأَعْرَابِيُّ فَطَفِقَ رِجَالٌ يَعْتَرِضُونَ الأَعْرَابِيَّ فَيُسَاوِمُونَهُ بِالْفَرَسِ وَلاَ يَشْعُرُونَ أَنَّ النَّبِيَّ صلى الله عليه وسلم ابْتَاعَهُ فَنَادَى الأَعْرَابِيُّ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ إِنْ كُنْتَ مُبْتَاعًا هَذَا الْفَرَسَ وَإِلاَّ بِعْتُهُ ‏.‏ فَقَامَ النَّبِيُّ صلى الله عليه وسلم حِينَ سَمِعَ نِدَاءَ الأَعْرَابِيِّ فَقَالَ ‏"‏ أَوَلَيْسَ قَدِ ابْتَعْتُهُ مِنْكَ ‏"‏ ‏.‏ فَقَالَ الأَعْرَابِيُّ لاَ وَاللَّهِ مَا بِعْتُكَهُ ‏.‏ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ بَلَى قَدِ ابْتَعْتُهُ مِنْكَ ‏"‏ ‏.‏ فَطَفِقَ الأَعْرَابِيُّ يَقُولُ هَلُمَّ شَهِيدًا ‏.‏ فَقَالَ خُزَيْمَةُ بْنُ ثَابِتٍ أَنَا أَشْهَدُ أَنَّكَ قَدْ بَايَعْتَهُ ‏.‏ فَأَقْبَلَ النَّبِيُّ صلى الله عليه وسلم عَلَى خُزَيْمَةَ فَقَالَ ‏"‏ بِمَ تَشْهَدُ ‏"‏ ‏.‏ فَقَالَ بِتَصْدِيقِكَ يَا رَسُولَ اللَّهِ ‏.‏ فَجَعَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم شَهَادَةَ خُزَيْمَةَ بِشَهَادَةِ رَجُلَيْنِ ‏.‏

Sunan Abi Dawud 3607 https://sunnah.com/abudawud:3607

If we accept this narration, it shows that Khuzaymah has a history of bearing false witness. Yet somehow, this narration is supposed to give us confidence in Khuzaymah's trustworthiness. The Quran is very clear that it is strictly prohibited ever to bear false witness.

[4:135] O you who believe, you shall be absolutely equitable, and observe GOD, when you serve as witnesses, even against yourselves, or your parents, or your relatives. Whether the accused is rich or poor, GOD takes care of both. Therefore, do not be biased by your personal wishes. If you deviate or disregard (this commandment), then GOD is fully Cognizant of everything you do.

يَاأَيُّهَا الَّذِينَ آمَنُوا كُونُوا قَوَّامِينَ بِالْقِسْطِ شُهَدَاءَ لِلَّهِ وَلَوْ عَلَىٰ أَنْفُسِكُمْ أَوِ الْوَالِدَيْنِ وَالْأَقْرَبِينَ إِنْ يَكُنْ غَنِيًّا أَوْ فَقِيرًا فَاللَّهُ أَوْلَىٰ بِهِمَا فَلَا تَتَّبِعُوا الْهَوَىٰ أَنْ تَعْدِلُوا وَإِنْ تَلْوُوا أَوْ تُعْرِضُوا فَإِنَّ اللَّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

The Quran uses some of the strongest language to prohibit the bearing of false witness by telling the followers of the Quran not only to not partake in such actions but to outright avoid it.

[22:30] Those who reverence the rites decreed by GOD have deserved a good reward at their Lord. All livestock is made lawful for your food, except for those specifically prohibited for you. You shall avoid the abomination of idol worship, and avoid bearing false witness.

ذَٰلِكَ وَمَنْ يُعَظِّمْ حُرُمَاتِ اللَّهِ فَهُوَ خَيْرٌ لَهُ عِنْدَ رَبِّهِ وَأُحِلَّتْ لَكُمُ الْأَنْعَامُ إِلَّا مَا يُتْلَىٰ عَلَيْكُمْ فَاجْتَنِبُوا الرِّجْسَ مِنَ الْأَوْثَانِ وَاجْتَنِبُوا قَوْلَ الزُّورِ

To show the seriousness of such an offense, this is the same language that is used in the prohibitions towards intoxicants, gambling, and the altars of idols.

[5:90] O you who believe, intoxicants, and gambling, and the altars of idols, and the games of chance are abominations of the devil; you shall avoid them, that you may succeed.

يَاأَيُّهَا الَّذِينَ آمَنُوا إِنَّمَا الْخَمْرُ وَالْمَيْسِرُ وَالْأَنْصَابُ وَالْأَزْلَامُ رِجْسٌ مِنْ عَمَلِ الشَّيْطَانِ فَاجْتَنِبُوهُ لَعَلَّكُمْ تُفْلِحُونَ