Is following up with potential buyers from other stores' pages to sell a specific product considered selling over another's sale?

It is forbidden for a Muslim to sell over his brother's sale or to bid over his bid, because the Prophet (peace be upon him) said: "Let not some of you sell over the sale of his brother," and "The believer is the brother of the believer, so it is not lawful for a believer to buy over the sale of his brother," and "A man should not propose over the proposal of his brother, nor should he bid over the bid of his brother."

Selling over one's brother's sale is like when the buyer says during the option period: "Cancel this sale, and I will sell you the like for cheaper or better quality." Bidding over one's brother's bid is when the owner and the interested party have agreed upon the sale but have not yet concluded the contract, and another person tells the seller: "I will buy it."

As for entering store pages and displaying goods to their visitors, if they have not yet bought or bargained, this does not fall under the prohibition. However, if one of them has bargained with the store and they have settled on a specific price, then it is not permissible to offer the item to him. If he inquired about specifications or price, or bargained without settling on a price, then it is permissible to offer the item.

If store owners prohibit displaying goods to their page visitors, then it is not permissible to do so. If they do not prohibit it, then there is no harm, but it is preferable to provide a link to the website or communicate with those who want the item from them.