If a person is subjected to an unfair disparity in price that exceeds customary limits, does he have the option to rescind the sale on that basis, or does he not?

Some scholars hold that he has no such option unless he stipulated it for himself as a safeguard. They cite the hadith of the man who complained to the Messenger of Allah ﷺ that he was being overcharged in sales. The Prophet ﷺ said to him: “When you enter into a sale, say: ‘No deception.’” Thereafter, whenever he bought or sold, he would say: “No deception.” (1) They said: The Messenger ﷺ instructed him to stipulate for himself that there be no khilābah (deception)—that is, no one should gain the upper hand over him. Had such unfair disparity entitled one to rescind without any stipulation, the Messenger ﷺ would have told him: “If you are overcharged, return what you were overcharged for,” rather than saying: “When you enter into a sale, say: ‘No deception.’”

This is the view of some scholars, and it is very strong. Others hold that this does establish the option, even if he did not stipulate it. They say: This is a form of deceit and betrayal; if we did not affirm the right of rescission, that would open the door to deceit and betrayal. The Sacred Law seeks to ward off harms and secure benefits. Since we know that this wards off harm and blocks the path of those who betray and deceive, it is obligatory to adopt this course.

This reasoning is strong, but it requires an answer to the hadith. For when a proponent considers his view stronger, he must bring supporting considerations as well as responses that refute his opponent’s view. They therefore say: The Messenger ﷺ only instructed him to stipulate it, despite its being established for him even without stipulation, for two reasons: