Narrated [Ibn 'Umar (RA)]:

Allah's Messenger (ﷺ) forbade bidding against one another (to raise the price). [Agreed upon].

وَعَنْهُ قَالَ: { نَهَى ‏- صلى الله عليه وسلم ‏-عَنِ النَّجْشِ } مُتَّفَقٌ عَلَيْهِ [1]‏ .‏