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 (PBUH) as having said this: One amongst you should not enter into a transaction when another is bargaining. Translation Not Available

Book Ref: Sahih Muslim Book 21 Hadith 3617
Web Ref:  Sahih Muslim Book 10 Hadith 1412 e