If a man has two wives, the one beloved and the one hated, and they bear him sons, the beloved and the hated, and the firstborn son is the hated one’s—
English: “And they bear him” — only one whose offspring are his; this excludes the child of a maidservant or a non-Jewish woman, whose offspring are not his.
On the daf / in context: The possessive “lo” requires that the children be legally his. Children of a shifchah or a non-Jewess follow the mother’s status and do not inherit from the Jewish father under the laws of this section.
Type of Learning
Mi’ut from the word “lo.”
What Is Learned
Only sons who are legally his count for the inheritance rules of this section; children of a maidservant or non-Jewess are excluded.