‘Amr b. Shu'aib, on his father’s authority, told that his grandfather reported the Prophet as saying, “Proof lies on the plaintiff and the oath is to be sworn by the defendant.”
Abu Huraira told that the Prophet suggested to some people that they should swear an oath and when they hastened to do so he ordered that lots should be cast among them concerning the oath as to who should swear it.
Umm Salama told on the Prophet’s authority about two men, who brought a dispute before him about inheritances, but had no proof beyond their claim. He said, “If I give a decision in favour of one respecting what is rightly his brother’s I am allotting him only a portion of hell.” Thereupon both the men said, “Messenger of God, this right of mine may go to my brother,” but he replied, "No; rather go and divide it up, aiming at what is right, then draw lots, and let each of you consider the other to have what is legitimately his.” In a version he said, “I judge between you only by my opinion regarding matters about which no revelation has been sent down to me.”
Ibn Mas'ud reported God’s Messenger as saying, “The best of men are my generation, then those who come next to them, then those who come next to them. Afterwards people will come who will give testimony before swearing an oath and swear an oath before giving testimony.”