By virtue of the international treaty which had been settled in Madīnah after the migration, in a way, the Holy Prophet(sa) had taken on the capacity of a political leader and judicial head for the various nations in Madīnah. It was as if the Holy Prophet(sa) had been declared the chief executive of the international democratic state, which had been established in Madīnah after the migration. In this position, cases of importance were submitted to the Holy Prophet(sa) and he would issue verdicts according to the judicial laws which regulated each segment of the population. There is a narration that towards the end of 4 A.H., the case of a Jewish man and a Jewish woman were presented before the Holy Prophet(sa), in which the charge of adultery was duly established against them. The Holy Prophet(sa) inquired of the Jewish scholars as to the edict that was given by the Mosaic law in this respect. By way of deception and falsehood they responded that according to their law, the penalty for a person who is guilty of adultery is that the face of the offender is blackened and he is then taken throughout the streets riding a mount, facing backwards. At the time, ‘Abdullāh bin Salām(ra) who was a Jewish scholar, but had now accepted Islām was sitting nearby and submitted, “O Messenger of Allāh! These people are lying. According to the Torah, the punishment for adultery is stoning to death.” Thus, a copy of the Torah was brought and although the Jews tried their utmost to conceal the truth, to the extent that they even tried to cover the relevant verse with their hands, ‘Abdullāh bin Salām(ra) clearly proved that in light of the Torah, the penalty for adultery is stoning, and they were made to face embarrassment. Since the treaty stated that cases of various nations would be settled according to their own respective laws, and no injunctions had been revealed with regards to the penalty for adultery, etc., therefore, the Holy Prophet(sa) decided according to the Jewish law that both of them should be stoned. Hence, this man and woman were both stoned. This incident took place towards the end of 4 A.H.1
1 Ṣaḥīḥul-Bukhārī, Kitābul-Ḥudūd, Bābur-Rajmi Fil-Balāṭ, Ḥadīth No. 6819
Tārīkhul-Khamīs Fī Aḥwāli Anfasi Nafīs, By Ḥusain bin Muḥammad bin Ḥasan, Volume 1, p. 467, Rajmul-Yahūdiyyīn, Mu’assasatu Sha‘bān, Beirut