by mutual consent.” (1)
Third, sound reasoning also requires this. For if we did not stipulate mutual consent, people would devour one another’s wealth: anyone who desired an item belonging to someone else could go to him and say, “I have bought it from you for such-and-such, whether you like it or not.” This would lead to chaos, disorder, enmity, and resentment.
His statement, “Thus, a sale by one compelled without right is invalid,” means that a sale made by someone compelled without right is invalid. The compelled person is one forced into selling—that is, one coerced into it. A sale by a compelled person is therefore invalid unless the coercion is justified. Thus, if an unjust ruler were to force someone to sell this item to a particular person, and he sold it, the sale would be invalid, since it did not proceed from mutual consent.
Similarly, if you know that a seller sold something to you only out of shyness and embarrassment, it is not permissible for you to buy it from him so long as you know that, were it not for his shyness and embarrassment, he would not have sold it to you. For this reason, the scholars, may Allah have mercy on them, said: It is unlawful to accept a gift when one knows that the man gave it merely out of shyness and embarrassment. Although he may not explicitly state that he is unwilling, the circumstances indicate that he is not consenting.
His statement, “Thus, a sale by one compelled without right is invalid,” indicates, may Allah have mercy on him, that if someone is compelled with right, there is no problem. This is because it is the enforcement of a right. That is, if we compel someone to sell rightfully, this is the enforcement of a right; it is neither injustice nor transgression.