Sanhedrin 53 - Shabbat February 8, 10 Shvat

What specific transgressions are punished by stoning? For some transgressions, the punishment is explicitly mentioned in the Torah, while for others it is derived from a gezeira shava using the words "demaihem bam" that appear in the context of a necromancer and a sorcerer. Why is the derivation is not made from the words "mot yumatu" instead. According to the version in the Mishna, Rabbi Yehuda holds a different view from the rabbis regarding a specific case: if a man has intercourse with his mother who is also his father's wife, he is only obligated once (in an accidental scenario, he would bring only one sin offering). The Gemara first presents an alternative version of Rabbi Yehuda's position, stating that if the mother was forbidden to marry the father, then the son is only obligated once for relations with his mother, not because she was his father's wife. To properly understand this interpretation, it seems that Rabbi Yehuda follows Rabbi Akiva's opinion that a marriage to someone forbidden by a negative prohibition is invalid. The version of Rabbi Yehuda in the Mishna is subsequently confirmed by Rabbi Yitzchak. Abaye, Rav Acha, and Rava each provide explanations for this version of Rabbi Yehuda. However, both Abaye and Rav Acha's suggestions are ultimately rejected.