Umara bin Khuzayma reported,

Khuzayma bin Thabit, who was one of the companions of the Prophet ﷺ, reported that the Prophet ﷺ bought a horse from an Arabi and asked him to follow him so he could pay him the price of the horse. The Prophet ﷺ walked on quickly, but the Arabi lagged behind. Some men began to approach the Arabi and bargain with him over the horse, not realizing that the Prophet ﷺ had already bought it. One of them eventually offered a higher price than what the Prophet ﷺ had purchased it for.The Arabi then called out to the Prophet ﷺ and said, "If you are buying this horse, take it. Otherwise, I will sell it."The Prophet ﷺ stopped when he heard him calling and said, "Have I not already bought it from you?"The Arabi replied, "No, by Allah, I have not sold it to you."The Prophet ﷺ said, "I have indeed bought it from you."People began to gather around the Prophet ﷺ and the Arabi as the two went back and forth, and the Arabi kept saying, "Bring a witness who can testify that I sold it to you."Khuzayma bin Thabit said, "I bear witness that you sold it to him."The Prophet ﷺ turned to Khuzayma and asked, "On what basis do you bear witness?"He replied, "On the basis of believing you, Messenger of Allah."So the Messenger of Allah ﷺ made Khuzayma's testimony equivalent to the testimony of two men.

أخبرنا الهيثم بن مروان بن الهيثم بن عمران قال حدثنا محمد بن بكار قال حدثنا يحيى وهو ابن حمزة عن الزبيدي أن الزهري أخبره

عن عمارة بن خزيمة أن عمه حدثه

وهو من أصحاب النبي ﷺ أن النبي ﷺ ابتاع فرسا من أعرابي واستتبعه ليقبض ثمن فرسه فأسرع النبي ﷺ وأبطأ الأعرابي وطفق الرجال يتعرضون للأعرابي فيسومونه بالفرس وهم لا يشعرون أن النبي ﷺ ابتاعه حتى زاد بعضهم في السوم على ما ابتاعه به منه فنادى الأعرابي النبي ﷺ فقال إن كنت مبتاعا هذا الفرس وإلا بعته فقام النبي ﷺ حين سمع نداءه فقال أليس قد ابتعته منك قال لا والله ما بعتكه فقال النبي ﷺ قد ابتعته منك فطفق الناس يلوذون بالنبي ﷺ وبالأعرابي وهما يتراجعان وطفق الأعرابي يقول هلم شاهدا يشهد أني قد بعتكه قال خزيمة بن ثابت أنا أشهد أنك قد بعته قال فأقبل النبي ﷺ على خزيمة فقال لم تشهد قال بتصديقك يا رسول الله قال فجعل رسول الله ﷺ شهادة خزيمة شهادة رجلين