the Prophet bought a horse from a Bedouin and asked him to follow him, so that he could pay him for the horse. The Prophet hastened but the Bedouin was slow. Men started to talk to the Bedouin and make offers for the horse, and they did not realize that the Prophet had bought it, until some of them offered more than the Prophet had bought it for. Then the Bedouin called out to the Prophet and said; "Are you going to buy this horse or shall I sell it?" The Prophet stood up when he heard him calling and said: "Have I not bought it from you?" He said: 'No, by Allah, I have not sold it to you, and the Prophet said "I bought it from you." The people started to gaiter around the Prophet and the Bedouion as they were talking, and the Bedouin started to say: "Bring a witness who will testify that you bought it. " Khuzaimah bin habit said: "I bear witness that you bought it" The Prophet turned to Khunzimah and said: "Why are you bearing witness?" He said: "Because I know that you are truthful, O Messenger of Allah" made the testimony of Khuzaimah equivalent to the testimony of two men. (sahih) (Using translation from Nasāʾī 4647)   

أَخْبَرَهُ وَكَانَ مِنْ أَصْحَابِ رَسُولِ اللهِ ﷺ أَنَّ رَسُولَ اللهِ ﷺ ابْتَاعَ فَرَسًا مِنْ رَجُلٍ مِنَ الْأَعْرَابِ فَاسْتَتْبَعَهُ لِيَقْضِيَهُ ثَمَنَ فَرَسِهِ فَأَسْرَعَ رَسُولُ اللهِ ﷺ الْمَشْيَ وَأَبْطَأَ الْأَعْرَابِيُّ وَطَفِقَ رِجَالٌ يَعْتَرِضُونَ الْأَعْرَابِيَّ فَسَاوَمُوهُ بِالْفَرَسِ وَلَا يَشْعُرُونَ أَنَّ رَسُولَ اللهِ ﷺ قَدِ ابْتَاعَهُ حَتَّى زَادَ بَعْضُهُمُ الْأَعْرَابِيَّ فِي السَّوْمِ عَلَى ثَمَنِ الْفَرَسِ الَّذِي ابْتَاعَهُ رَسُولُ اللهِ ﷺ فَلَمَّا زَادَهُ نَادَى الْأَعْرَابِيُّ رَسُولَ اللهِ ﷺ فَقَالَ إِنْ كُنْتَ مُبْتَاعًا هَذَا الْفَرَسَ فَابْتَعْهُ أَوْ لَأَبِيعَنَّهُ فَقَامَ رَسُولُ اللهِ ﷺ حِينَ سَمِعَ نِدَاءَ الْأَعْرَابِيِّ حَتَّى أَتَاهُ الْأَعْرَابِيُّ فَقَالَ لَهُ أَوَلَسْتُ قَدِ ابْتَعْتُهُ مِنْكَ؟ فَقَالَ الْأَعْرَابِيُّ لَا وَاللهِ مَا بِعْتُكَ قَالَ فَقَالَ رَسُولُ اللهِ ﷺ بَلَى قَدِ ابْتَعْتُهُ مِنْكَ فَطَفِقَ النَّاسُ يَلُوذُونَ بِرَسُولِ اللهِ ﷺ وَبِالْأَعْرَابِيِّ وَهُمَا يَتَرَاجَعَانِ وَطَفِقَ الْأَعْرَابِيُّ يَقُولُ هَلُمَّ شَهِيدًا يَشْهَدُ أَنِّي بَايَعْتُكَ فَمَنْ جَاءَ مِنَ الْمُسْلِمِينَ قَالَ لِلْأَعْرَابِيِّ وَيْلَكَ إِنَّ رَسُولَ اللهِ ﷺ لَمْ يَكُنْ يَقُولُ إِلَّا حَقًّا حَتَّى جَاءَ خُزَيْمَةُ فَاسْتَمَعَ مَا يُرَاجِعُ رَسُولُ اللهِ ﷺ وَيُرَاجِعُ الْأَعْرَابِيُّ وَطَفِقَ الْأَعْرَابِيُّ يَقُولُ هَلُمَّ شُهَدَاءُ يَشْهَدُونَ أَنِّي بَايَعْتُكَ قَالَ خُزَيْمَةُ أَنَا أَشْهَدُ أَنَّكَ قَدْ بَايَعْتَهُ فَأَقْبَلَ رَسُولُ اللهِ ﷺ عَلَى خُزَيْمَةَ قَالَ بِمَا تَشْهَدُ؟ قَالَ بِتَصْدِيقِكَ يَا رَسُولَ اللهِ فَجَعَلَ رَسُولُ اللهِ ﷺ شَهَادَةَ خُزَيْمَةَ شَهَادَةَ رَجُلَيْنِ وَاللهُ أَعْلَمُ