If they are both content with it, it is permissible. It does not follow from their being content with one oath that each one holds a portion of the oath, just as when rights are established by a single evidence, it does not mean that each right holds a portion of the evidence. However, if he requires them all to take a single oath without their consent, his requiring the oath is invalid, according to a consensus we are aware of. Al-Istakhri narrated that Isma'il ibn Ishaq, the judge, required a man to take a single oath for a right belonging to two men, and the people of his time deemed him to be in error. If the claimant says: 'I have absent evidence,' the judge says to him: 'You have the right to his oath; if you wish, you may require him to take it, and if you wish, I will delay the matter until you bring your evidence.' You do not have the right to demand a guarantor from him, nor to detain him until you produce the evidence. Ahmad explicitly stated this, and it is the school of al-Shafi'i, based on the saying of the Messenger of Allah (may Allah bless him and grant him peace): 'Your two witnesses or his oath; you have nothing else but that.' If he requires him to take the oath, and then his evidence arrives, he shall judge by the evidence. The oath does not nullify the right, because the oath is only resorted to when there is no evidence; when the evidence is found, the oath is nullified, and its falsehood becomes apparent. If he says: 'I have present evidence, and I want his oath, then I will produce my evidence,' he does not possess the right to do so. Abu Yusuf said: He should require him to take the oath, and if he refuses, he should rule against him, because there is benefit in requiring the oath—for he might refuse, and [the judge] would rule against him, thereby rendering the evidence unnecessary. Our view is based on his (peace be upon him) saying: 'Your two witnesses or his oath; you have nothing else but that.' The 'or' here indicates a choice between two things, so he cannot combine them. Furthermore, it is possible to resolve the dispute with evidence, so no other method is legislated when the claimant wishes to produce it and it is present, just as if he had not sought his oath. Additionally, the oath is a substitute, so it is not required to combine it with that which is substituted, just like all other substitutes with their originals. If the claimant says: 'I do not want to produce it; I only want his oath, and I will be satisfied with that,' he is made to take the oath, because the evidence is his right, and if he is satisfied with dropping it and leaving it unproduced, he may do so, just as with the right itself. If the defendant takes the oath, then the claimant wishes to produce his evidence, does he have the right to do so? There are two possibilities: one is that he may do so, because the evidence is not invalidated by the taking of the oath, just as if it had been absent. The second is that he does not have the right to do so, because he has already forfeited his right to produce it, and because allowing its production opens the door to stratagem, for he might say: 'I do not want to produce it,' so that his opponent swears, and then he produces it.