Does informing another broker of a higher price offer for a plot of land for sale constitute "buying over one's brother's sale" if no contracts have been written yet, and must the first party be informed of the second offer?

There is no harm in offering the land to another broker and informing him of the brokers' price before the sale is finalized and the price is settled. The prohibition against a man selling over his brother's sale or bidding over his bid applies after explicit agreement on the price. The first broker must be informed of the price that has been reached, to safeguard the owner's interest, and if it is highly probable that there is no higher price, then the sale can proceed. The scholars have stated that the broker is obligated to sell at the highest price, otherwise he should be prevented from brokering.