The prohibition of urging a buyer to cancel a purchase in order to sell him one's own goods; And urging a seller to cancel a sale already agreed upon so that one can buy the goods oneself; And the prohibition of artificially inflating prices; And the prohibition of letting milk accumulate in the udder in order to deceive the purchaser Sahih Muslim 1412 e
Arabic hadith text
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ "لاَ يَبِعْ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ "
Translation
Ibn 'Umar (Allah be pleased with them) reported Allah's Messenger (ﷺ) as having said this
One amongst you should not enter into a transaction when another is bargaining.