حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنِ النَّجْشِ ‏.‏

Ibn Umar (Allah be pleased with them) reported that Allah's Messenger (PBUH) forbade the outbidding (against another). Translation Not Available

Book Ref: Sahih Muslim Book 21 Hadith 3622
Web Ref:  Sahih Muslim Book 10 Hadith 1516