Then it shall be, on the day he causes his sons to inherit that which he has, that he may not make the son of the beloved the firstborn before the son of the hated, the firstborn.
English: “Before” (al penei) — this teaches that once the head and the majority of the body have emerged while alive, that child exempts any subsequent child from the status of firstborn.
On the daf / in context: The phrase “al penei” is taken to mean the emergence of the head (or majority). Once a viable first child has been born, later sons cannot claim the bechorah even if the first later dies.
Type of Learning
Derash on “al penei” defining the moment that establishes firstborn status.
What Is Learned
Once a child’s head and majority have emerged alive, that child is the firstborn; any later son is exempt from the double portion.