The Ruling on Selling on the Sale of One's Brother

Question:
And other things. Sometimes the sellers have the ability to be stingy, for example. He prices the item at five riyals and agrees with him that he will take it for five riyals after he leaves. Then another person comes and offers six riyals for it. Is it permissible for him to sell to the other person at a better price?

Answer:
Do not hold back as long as you have not finalized the deal. First of all, yes, there is no going back once the buyer or the seller has left and they have separated, for the sale is then concluded. It is not permissible for anyone to sell over the sale of his brother, and if he has started well, it is not permissible. Indeed, the Messenger (peace and blessings be upon him) forbade this; he prohibited it. Once the sale is completed, it is not permissible. But you may say to the partner, or say to the seller, or say to the buyer, "I have something better than this item." This is what causes resentment and enmity. Yes. And if the owner of the item raises the price, meaning if someone comes to you and you sell to him. If the owner of the item stipulates that the price be increased, but they have not separated and the sale has not been completed between them, he can no longer stipulate. Sovereignty. I will get it for you if someone else comes and raises the price. I will sell it to you. If they agreed on it, the type was not specified.