If a man has a wayward and rebellious son who does not listen to the voice of his father and the voice of his mother, and they discipline him but he does not listen to them,
English: “A son to a man” — when Rav Dimi came he said: they say in the West, “if a man has a wayward and rebellious son” — a son, and not one who is fit to be called a father.
On the daf / in context: Once three months have passed after the appearance of pubic hair the youth is already capable of fathering a child and is therefore excluded. The entire window of liability is only about three months.
Type of Learning
Derash limiting the upper age of liability.
What Is Learned
The law of the wayward and rebellious son applies only during a brief period near the onset of manhood; once the youth is fit to be called a father he is no longer subject to it.