Malik said, from Nafi from Abdullah ibn Umar that the Messenger of Allah ﷺ forbade najsh. Malik said, "Najsh is to offer a man more than the worth of his goods when you do not mean to buy them and someone else follows you in bidding."
أنَّ رَسُولَ اللَّهِ ﷺ: «نَهى عَنِ النَّجْشِ» قالَ مالِكٌ: «والنَّجْشُ أنْ تُعْطِيَهُ بِسِلْعَتِهِ أكْثَرَ مِن ثَمَنِها، ولَيْسَ فِي نَفْسِكَ اشْتِراؤُها فَيَقْتَدِي بِكَ غَيْرُكَ»