But he shall acknowledge the firstborn, the son of the hated, by giving him a double portion of all that is found with him; for he is the first of his strength, the right of the firstborn is his.
English: “He shall acknowledge” — Mar the son of Rav Yosef said in the name of Rava: a firstborn born after the father’s death does not take a double portion. Why? The Merciful One said “he shall acknowledge,” and here there is none (the father is already dead).
On the daf / in context: The requirement of acknowledgment presupposes a living father who can identify the child. A posthumous birth therefore does not receive the bechorah.
Type of Learning
Derash requiring the possibility of paternal acknowledgment.
What Is Learned
A firstborn born after the father’s death does not receive the double portion.