An oath is one of the proofs of a lawsuit, and it consists of taking God's witness for news that is right for one's own benefit and to the detriment of another. Leaving the fate of the dispute to the oath as a spiritual tool is done in cases where no other valid reason can be presented to prove the subject of the dispute. In such a case, either the plaintiff's claim should be accepted without reason or a judgment should be issued against her, which neither of these two solutions is based on justice and there is a possibility of losing the right. In view of this problem, the legislator, by foreseeing a legal institution called oath, has left the fate of the lawsuit to the conscience to reveal the truth by relying on God and fearing the punishment of perjury. Considering the importance of the subject, this article has examined the role of oath in proving civil claims in Afghan law, and also evaluated the possibility and impossibility of realizing the conflict between the decisive oath and other proofs of the claim and concluded that the possibility of realizing There is no conflict between oath and other evidence.