Bidding for commodities

Question 40: Is bidding the price of commodities permissible in Sharee‘ah (Islaamic law) or not?

Answer: It is permissible to bid the price of commodities to preserve the seller’s right, unless the seller accepts the outbidding of one of the bidders, in which case further outbidding becomes impermissible, in order to protect the right of the person who made an agreed bid. This is what is meant by forbidding outbidding the bid of one’s brother… read more here.