Mishnayos Sanhedrin Perek 9 Mishnah 3

With regard to a murderer who was intermingled with others and it is not possible to identify the murderer, all of them are exempt from liability to be executed. Rabbi Yehuda says: The court gathers them into the vaulted chamber [lakippa] where they will eventually die. With regard to all those liable to be executed with different court-imposed death penalties who became intermingled with each other and it cannot be determined which individual was sentenced to which death, they are all sentenced to the most lenient form of execution to which any of them was sentenced. In a case where those who are liable to be stoned were intermingled with those who are liable to be burned, Rabbi Shimon says: They are all sentenced to be executed by stoning, as burning is a more severe form of execution than stoning. And the Rabbis say: They are all sentenced to be executed by burning, as stoning is a more severe form of execution than burning. Rabbi Shimon said to the Rabbis: If burning were not more severe than stoning, it would not have been administered to a priest’s daughter who committed adultery. A betrothed daughter of an Israelite who committed adultery is executed by stoning. If burning were not a more severe form of execution than stoning, it would not have been administered to the daughter of a priest who committed adultery, who would presumably receive a more severe punishment. The Rabbis said to Rabbi Shimon: If stoning were not more severe than burning it would not have been the death penalty administered to a blasphemer and to an idol worshipper, as their actions violate the very core of the Jewish faith. There is a parallel dispute: In a case where those who are liable to be killed by beheading were intermingled with those who are liable to be strangled, Rabbi Shimon says: They are all sentenced to be beheaded with a sword, as strangulation is a more severe form of execution than beheading. And the Rabbis say: They are all sentenced to be executed by strangulation, as beheading is a more severe form of execution than strangulation.