Tirmidhi

‘Abdullah bin Mas’ud (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings of Allah be upon him) said: “When there is a dispute between the seller and the buyer, the statement of the seller will be accepted, and the buyer will have the choice.” © Imam Tirmidhi says:
1- This hadith is mursal; ‘Awn bin ‘Abdullah did not meet Ibn Mas’ud,
2- And this hadith is also narrated from Qasim bin ‘Abdur-Rahman, who narrated from Ibn Mas’ud, and Ibn Mas’ud narrated from the Prophet (peace and blessings of Allah be upon him). And this narration is also mursal,
3- Ishaq bin Mansur says: I asked Ahmad: When there is a dispute between the seller and the buyer and there is no witness, whose statement will be accepted? He said: The statement of the owner of the goods will be considered, or both should take back their respective things, i.e., the seller takes back the goods and the buyer takes back the price. Ishaq bin Rahwayh also said the same as Ahmad,
4- And whoever’s statement is accepted, he will have to take an oath. © Imam Tirmidhi says:
It is narrated in the same way from some of the scholars among the Tabi’in, among whom is Shurayh.