The burden of proof in the Islamic-Ottoman judicial law is in principle a duty of the plaintiff, and the oath is among the defendant’s obligations. Oath, which is one of the means of proof in the Islamic judicial law, is that one of the parties making a declaration on behalf of God about the correctness of the event in the disputes submits to the court. The Qur’an and Sunnah constitute the legal basis for the use of oath evidence as a proof in Islamic law. On the other hand, in order to be able to offer oath to the defendant; there must be a lawsuit filed before the court, the defendant must reject the alleged claim, the plaintiff must not prove his claim and demand an oath, the oath must be brought before the judge or the regent and the oath must be brought to the defendant in person. Likewise, the fact that the subject of the case is transferable and reputable is one of the conditions for the application of the oath evidence in legal disputes, and the subject of the case is not necessary for the rights of God. In this context, if the plaintiff cannot prove the subject matter of the case, an oath is offered to the defendant in the presence of the judge or his regent who is in charge of looking at the case at his request. The fact that the defendant, who was offered oath, constitutes evidence in favor of the oath, is an evidence against him. However, in Islamic law, only oath is permitted in the name of God, and regardless of the religious affiliation of the oath, the oath on another being other than Allah is legally void.