The Jews came to the Messenger of Allah (may Allah's peace and blessings be upon him) and informed him that a man and woman from among them had committed unlawful sexual intercourse.

When a man and a woman from among the Jews committed adultery during the Prophet's time, the Jews came to the Prophet (may Allah's peace and blessings be upon him) seeking his judgment in the hope that they would get something lighter than the punishment of adultery in the Torah, which is stoning. So, the Prophet (may Allah's peace and blessings be upon him) asked them about Allah's judgment in the Torah, only to expose them, not to act upon it. They lied to him, saying that the judgment was to expose the adulterers. On hearing that, ‘Abdullāh ibn Salām (may Allah be pleased with him) said that they were lying. When they checked the Torah, they found the ruling of adultery, which is stoning the married adulterer. Hence, the Prophet (may Allah's peace and blessings be upon him) commanded the punishment to be inflicted on the adulterers.
Our Islamic law is dominant over any other law and abrogates it. In this Hadīth, however, the Prophet (may Allah's peace and blessings be upon him) asked them about the ruling of the Torah on stoning the adulterer in order to establish the argument against them through their own book, which they claimed that it did not include the ruling of stoning the married adulterer. Furthermore, he aimed thereby to show them that all the books of Allah are in agreement on that eternal ruling which involves deterrence to the sinners.