His statement, “or if it heals,” means that if the tooth heals, the lease is terminated. For example, a man’s tooth becomes inflamed and swollen, so he hires a dentist to extract it. Then Allah, Glorified be He, grants him healing: the swelling subsides and the pain ceases. The lease is then terminated, because he hired him to extract the tooth due to its pain and illness, not because he simply did not want the tooth.
If a dispute arises between the dentist—who has brought his instruments, prepared himself, and set aside time to extract this tooth—and the owner of the tooth, with the latter saying, “The pain has subsided and it has healed,” while the dentist says, “It has not healed,” then whose word is accepted? The owner of the tooth is believed upon taking an oath.
If the owner of the tooth claims that the pain has subsided because he knows that the dentist will charge a large fee, this is a possibility. Yet even if it is conceivable, we do not accept it, because whether it has healed or not can only be known from his side. If the dentist says, “I will give him cold water to drink; if his expression changes or he clenches his jaws, we will know that it has not healed; otherwise, it has healed,” then, if it is said that this test will achieve the intended result, we test him.
This is like what the scholars have said regarding bodily injuries: when a person is injured and claims to have lost his hearing. It is known that if a man is injured and loses his hearing, the offender is liable for the full blood-money of one hundred camels. The offender says, “He has not lost his hearing at all,” while the injured person says, “I have lost my hearing.” They said: he should be tested by approaching him unawares and shouting at him. If he reacts, then he is lying in his claim that his hearing has gone; but if he does not react, then he is truthful. There is no doubt that this is among the indications that establish the matter.
The same applies to sight. They said: if he claims that his sight was lost as a result of the injury, he should be tested: someone should catch him unawares and then place his hand near his eye. If he blinks, he can see; otherwise, he cannot.