The 331st prohibition is that one is forbidden from having relations with one's father's wife.1

The source of this commandment is G‑d's statement,2 "You must not commit incest with your father's wife."

The punishment for violating this prohibition is kares.3 If there were witnesses, and the act was intentional, the punishment is execution by stoning.4 If the act was unintentional, he must bring a sin-offering.5

It is therefore clear that one who commits incest with his mother is culpable both for incest with one's mother [N330] and with one's father's wife [N331]. This is true both during the father's lifetime and after his death, as explained in Sanhedrin.6