Our sedra is the tale of ‘sibling rivalries;’ an ancient Jewish tradition, it seems. The sedra opens with Rivkah’s twins (Yaakov and Eisav), and it continues with Eisav selling the firstborn rights to Yaakov, Yaakov then getting the firstborn blessings from (a now-blind) Yitzchak, and Yaakov fleeing to Padan Aram to escape Eisav. We are going to focus on the rather interesting sale of the firstborn rights which took place between Eisav and Yaakov, as detailed in 25:31-34. The question was already posed in the time of the Rishonim how could a sale of the firstborn right be effected and valid? Let’s explain.
The halacha is that ‘one cannot sell a commodity which does not yet exist’ (ein adam makneh davar she’lo ba le’olam) - such a sale does not go through. Now the firstborn rights are an example of such a ‘commodity which does not yet exist,’ for they only apply when the father is no longer living (the classic firstborn right is that of a double portion of inheritance, which only applies after the father’s death). If so, how could Eisav’s sale of the firstborn rights be a valid sale; and the pasuk says that a real sale did take place - ‘and he sold his firstborn (rights) to Yaakov’ (25:33). How could the sale go through? There is a relatively easy way out of this question, and it might be the explanation of the Ibn Ezra here. He seems to suggest that one aspect of the firstborn rights is that the other children have a duty to honour the firstborn, which would seem to apply even during the lifetime of the father.
If so, at least one aspect of the firstborn rights do exist currently, and thus the sale will go through like a normal sale. However, such an explanation is not agreed upon by everyone, and is not at all simple. Thus, we move on to the more solid, or conventional approaches to our question… The Rivash answers simply that before the Torah was given, the rules of sales were different; one could, indeed, sell a commodity which does not yet exist. The Tur, however, quotes his father the Rosh, who gives a different answer. He answers that though one normally cannot sell a commodity which currently does not exist, one can effect such a sale if the sale is accompanied by an oath - and here the pasuk (25:33) attests that Yaakov made sure that Eisav made this accompanying oath before the sale was carried through. What is behind this dispute between the Rivash and the Rosh?
Seemingly, they have different understandings of the problem of selling a commodity which does not yet exist, as we shall see. There are two ways to understand why such a sale does not go through. In every sale, there must be two components: a) an act of acquisition (for example, lifting up the object which is going to be acquired) and b) a firm, clear mindset of the buyer and seller that such an acquisition is taking place (I.e. intention to buy and sell). Thus, does selling a commodity that does not yet exist negate the existence of the act of acquisition or the intention of acquisition? This is a dispute dating back to the times of the Rishonim, and we shall explain these two options more clearly. Some hold that the problem of selling a currently non-existent commodity is that there can be no (clear show of) intention to buy such an object; the very fact that it does not yet exist means that there is nothing for the seller’s mindset to concretise/crystallise on in forming a solid, manifest intention to buy (and the same goes for the seller’s intention to sell). Others say that the problem is not in the intention/mindset component of the sale, but rather in the act of acquisition component - an act of acquisition has no power to effect a (future) sale of a commodity which does not yet exist. It would seem that this is the root of our dispute between the Rivash and Rosh. The Rosh held that the problem of selling a currently non-existent commodity is that there is no solid intention to effect a sale. Thus, when there is an accompanying oath, this oath provides the intention of sale. But the Rivash held that the problem of selling such a commodity relates to the act of acquisition, and so he held that the existence of an oath does not alter things, and so had to come onto his answer that the rules of acquisition pre-Mattan Torah were different. There are a few other answers to this question of how the sale of the firstborn rights went through…
The Ketzos HaChoshen holds that even though one cannot sell a currently non-existent commodity, one can give up one’s rights in such a commodity - and so here, Eisav simply gave up his rights in the firstborn. This needs further explanation; one would have to explain how Yaakov then ended up getting the rights, and it does not seem to fit brilliantly well with the wording of the psukim, which seem to attest that a sale took place. The Ohr HaChaim here says that he understands the problem of selling the currently non-existent commodity to be rooted in lack of intention to create a sale, but holds that an oath would not provide the requisite intention. Therefore, the Ohr HaChaim goes on to base the validity of the sale here on a unique halacha of kedei chayav, which dictates that a poor fisherman may sell ‘anything I catch today’ even though these fish are commodities which do not yet exist (in the seller’s possession).
So too, was Yaakov’s purchase of the firstborn rights a unique kedei chayav exception due to the importance of the sale and Eisav’s extreme hunger (he sold the rights for some lentil soup). In addition, Rav Osher Weiss cites those who understand that the act of acquisition in this sale of the firstborn rights were special, rarer forms of acts of acquisition, which according to some can even effect the sale of currently non-existent commodities. See footnote for brief details. We’ll end with n insightful observation about the sale of the firstborn rights which I once heard. Eisav sold the firstborn rights for lentil soup. Why was Yaakov cooking lentil soup that day? As Rashi comments, that day was the day that Avraham Avinu died, and lentils are traditionally eaten by mourners, for certain symbolic reasons cited by Rashi here. This tells us a lot about who Yaakov and Eisav were and what their priorities in life were. Death (especially of a close relative) is something that normally makes one think. One thinks about how short life is and one tends to focus on what one wants to achieve in one’s short stay in this world; ‘what will they say about me after I’m no longer here?’ The only priority on Eisav’s mind during such a day was to fill his stomach and to get rid of the glorious rights of the firstborn; which included serving in the Mikdash in the future. Yaakov also focussed on his priorities upon the death of his grandfather Avraham. Yaakov realised that he wanted to achieve closeness to HaShem, and that the wicked Eisav does not deserve the job of offering sacrifices to HaShem in the Mikdash - this should be Yaakov’s role. And so Yaakov went about achieving this goal and bought the firstborn rights. Often we are so mesmerised and distracted by the hustle and bustle of fast-moving everyday life that we do not have a chance to work out our priorities in life, let alone focus on achieving them. What do I want to be? What do I want people to say about me after 120? What legacy do I want to leave my children with? This portion of Yaakov and Eisav teaches us that sooner or later, one must carefully weigh up one’s priorities and make every effort to follow them. Have a great Shabbos!  Shulchan Aruch Chosen Mishpat 209:4  Ibn Ezra 25:31 in one of his two explanations. Though see Ibn Ezra on pasuk 32 which seems to say that no aspects of the bechorah apply whilst the father is still alive.  Assuming that the parts of the bechorah are not severed to only allow the currently existing parts of the bechorah to go through as part of the sale, whilst the other parts of the bechorah (e.g. double inheritance) which do not exist yet do not go through with the sale. Rav Osher Weiss does cite such a concept of ‘since some parts of a commodity are valid to be sold, they allow the other, non-valid, parts of the commodity to be sold too.  The ‘since…’ is not so simple, and not all agree that the duty to honour the firstborn applies whilst the father is still alive; though the Ramban in his comments to the Rambam’s Sefer HaMitzvos, shoresh beis says that it does (the Ramban is cited by the Minchas Chinuch 33:1).  Rivash siman 328 (he is cited by the Ketzos HaChoshen 209:4 and 278:13)  Parenthetically, the Rivash’s answer is not so easy to digest. If before Mattan Torah such a sale could exist, this would mean that al pi svora one could sell commodities which do not yet exist; just when the Torah was given, the Torah mandated that these sales cannot exist. But I am aware of no such pasuk which bans the sale of commodities which do not currently exist (regulating what is sold is not Torah realm generally; it depends on the intentions and agreement of the buyer and seller) - on the contrary, the reason one cannot sell such a commodity is al pi svora. Unless perhaps the Rivash holds that same psukim which instituted the ways of acquisition (kinyanim) automatically banned selling our non-existent commodity, for the kinyan cannot tap into such a commodity [and that would mean that the Rivash holds that the various darchei kinyan are mide’oraisa, which is not so simple].  Also brought by the Ketzos HaChoshen  Sefer HaYashar of Rabeinu Tam, 592  HaMekach VeHamemkar of Rav Hai Gaon, sha’ar 72  Perhaps one would have to say that once the biological firstborn forgoes his rights, the rights automatically pass down to the second child (though why should that be; does there need to be a firstborn?)  Perhaps because the oath was made by the seller, but the buyer has not demonstrated any intention (the Rosh would hold that the fact that the buyer asked the seller to make an oath was a demonstration of his intention to effect a sale). Alternatively, the dispute might hinge on whether one can use a proof of intention outside the act of acquisition to effect a sale.  Minchas Osher, parshas Toldos  The Sforno learns that this was a kinyan chalipin, and the Rashbam learns that it was a kinyan situmta, and in both of these kinyanim there are those who hold that they can effect a kinyan of even a commodity which does not currently exist; Mordechai, Shabbos 473, and Ra’avid in Shut Tamim De’im siman 160.  I heard it from Rabbi Horn; he quoted someone else, but I can’t remember who  Rashi 25:30