وَحَدَّثَنِي مَالِكٌ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ مَسْعُودٍ، كَانَ يُحَدِّثُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَيُّمَا بَيِّعَيْنِ تَبَايَعَا فَالْقَوْلُ مَا قَالَ الْبَائِعُ أَوْ يَتَرَادَّانِ " .
Malik related to me that he had heard that Abdullah ibn Masudused to relate that the Messenger of Allah, may Allah bless him andgrant him peace, said, "When two parties dispute about a businesstransaction, the seller's word is taken, or they make an agreementamong themselves. Malik spoke about someone who sold goods toa man, and said at the contracting of the sale, 'I will sell to youprovided I consult so-and-so. If he is satisfied, the sale ispermitted. If he dislikes it, there is no sale between us.' They madethe transaction on that basis. Then the buyer regretted before theseller consulted the person. Malik said, "That sale isbinding on them according to what they described. The buyer has noright of withdrawal, and it is binding on him, if the person whom theseller stipulated to him, permits it." Malik said, "The wayof doing things among us about a man who buys goods from another andthey differ about the price, and the seller says, 'I sold them to youfor ten dinars,' and the buyer says, 'I bought them from you for fivedinars,' is that it is said to the seller, 'If you like, give them tothe buyer for what he said. If you like, swear by Allah that you onlysold your goods for what you said.' If he swears it is said to thebuyer, 'Either you take the goods for what the seller said, or youswear by Allah that you bought them only for what you said.' If heswears, he is free to return the goods. That is when each of themtestifies against the other." Translation Not Available
Book Ref: Muwatta Imam Malik Book 31 Hadith 1368
Web Ref: Muwatta Imam Malik Book 31 Hadith 81