The Book of Transactions
21/4. Chapter:
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
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 " .
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.
Reference : Sahih Muslim 1412eIn-book reference : Book 21, Hadith 11USC-MSA web (English) reference : Book 10, Hadith 3617