כִּי֩ אֶת־הַבְּכֹ֨ר בֶּן־הַשְּׂנוּאָ֜ה יַכִּ֗יר לָ֤תֶת לוֹ֙ פִּ֣י שְׁנַ֔יִם בְּכֹ֥ל אֲשֶׁר־יִמָּצֵ֖א ל֑וֹ כִּי־הוּא֙ רֵאשִׁ֣ית אֹנ֔וֹ ל֖וֹ מִשְׁפַּ֥ט הַבְּכֹרָֽה׃ (ס)
Kundi kikilalanin niya bilang panganay ang anak ng kinapopootan, sa pamamagitan ng pagbibigay sa kanya ng dalawang bahagi sa lahat ng nasa kanyang pag-aari, sapagkat siya ang unang bunga ng kanyang lakas; sa kanya ang karapatan ng pagkapanganay.
Rashi
פי שנים A DOUBLE PORTION — i.e. a portion equal to those of two brothers together (Sifrei Devarim 217:2-4).
Chizkuni
בן השנואה יכיר, “he must recognise the son of the “hated” wife as his firstborn. The reason why the Torah chose the expression “recognise” here is that usually when someone wishes to deny a relative some favour that the latter claims he is entitled to, he behaves as if he does not even ”know” such a person. We find an example of this expression in such a situation when Joseph’s brothers came to Egypt to buy grain and he pretended not to know who they were, i.e. ויתנכר, (Genesis 42,7). The Torah there had told us that he had recognised them immediately. On the other hand, when Boaz treated Ruth, whom he had never even met, with kindness and consideration, (Ruth 2,10) she is so astounded that she asked him what prompted him to treat her as if he had known her for a long time, מדוע מצאתי חן בעיניך, “what caused me to have found favour in your eyes, ואני נכריה, when I am a complete stranger?”The Torah demands of the father of his biological and chronological firstborn to introduce him as such to anyone who does not know him. Moreover, Jewish law decrees that when a father introduces his son in such a way he is trustworthy and does not have to provide independent proof for his claim. (Talmud, tractate Kidushin, folio 74.)
Ibn Ezra
recognize He must grant him a formal recognition. or He must publicly designate him to be the firstborn, if he is in a place where he is not known. or He is obliged from the beginning to recognize which of his sons is the elder, in the case when there were twin boys.
Siftei Chakhamim
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Para lamang sa mga Premium memberRashi
בכל אשר ימצא לו [BUT HE SHALL ACKNOWLEDGE THE SON OF THE HATED FOR THE FIRSTBORN, BY GIVING HIM A DOUBLE PORTION] OF ALL THAT SHALL BE FOUND WITH HIM — From here the Rabbis derived the law that the firstborn does not receive a double share of what is due to come after the death of the father (as, e.g., a debt or a legacy that were payable to his father on a certain date, before which, however, the father died — technically termed ראוי), as he does of what is actually held in possession by the father (מוחזק) (Sifrei Devarim 217:6; Bekhorot 51b).