What is the ruling on taking money in exchange for withdrawing from a public auction, if the one entering it intends to buy and not to bid up the price without intending to buy (najsh)?

This is a disputed issue. The permissibility of it is conditioned on the expulsion of one participant from the auction being for someone not considered a leader (or not to be followed), and not an expulsion of all those interested in buying. Also, the remaining bidders must not collude to not exceed a certain price, as this involves injustice and harm to the seller.