Talmud - Bekhorot 49b בכורות מ״ט ב׳

Here, too, the halakha is no different.

And Shmuel could say to you: There, with regard to betrothal, it is in his power to betroth her from now, when he gave her the coins, and therefore it is irrelevant that the money was spent. Conversely, here, in the case of redemption, it is not in his power to redeem his son from now. With regard to the practical halakha in this dispute the Gemara comments: And even though we maintain as a principle that wherever Rav and Shmuel disagree the halakha is in accordance with the opinion of Rav in ritual matters and in accordance with the opinion of Shmuel in monetary matters, here the halakha is in accordance with the opinion of Shmuel, who holds that if one redeems his son within thirty days he is not redeemed.

The Gemara raises a difficulty: We learned in the mishna on the previous amud: If the firstborn son dies within thirty days of birth, although the father gave five sela coins to the priest, the priest must return the five sela coins to him. The Gemara infers: The reason he must return the money is that the son died. But if he did not die within thirty days his son is redeemed despite the fact that the father gave the priest the money prior to the proper time. This inference contradicts the opinion of Shmuel. The Gemara answers: Here we are dealing with a case where the money is still extant, i.e., in the priest’s possession.

The Gemara comments: Come and hear another difficulty from the mishna: If the father of the firstborn son dies within thirty days of the birth the presumptive status of the son is that he is not redeemed, until people will tell him that he is redeemed. But if people tell him he is redeemed then the redemption is effective, in contradiction to the opinion of Shmuel. The Gemara answers: There too, it is referring to a case where the money is still extant, i.e., in the priest’s possession.

The Gemara relates that a tanna taught a baraita in the presence of Rav Yehuda: In the case of one who redeems his firstborn son within thirty days of his birth, his son is redeemed. Rav Yehuda said to him: Shmuel said his son is not redeemed, and yet you say his son is redeemed? The Gemara comments: And even though we maintain that the halakha is in accordance with the opinion of Rav in ritual matters and in accordance with the opinion of Shmuel in monetary matters, here the halakha is in accordance with the opinion of Shmuel.

§ The mishna teaches that if one had both himself to redeem and his son to redeem, his own redemption takes precedence over that of his son. The Sages taught in a baraita: If one had both himself to redeem and his son to redeem, his own redemption takes precedence over that of his son. Rabbi Yehuda says: The redemption of his son takes precedence, as the mitzva to redeem the father is incumbent upon his own father, and the mitzva to redeem his son is incumbent upon him. Consequently, he should first fulfill the mitzva that is incumbent upon him by redeeming his son.

Rabbi Yirmeya says: Everyone concedes that in a case where there are only five sela coins available and one has to redeem both himself and his son, his own redemption takes precedence over that of his son, despite the indication to the contrary from the mishna. What is the reason? The reason is that his own mitzva is preferable to one he performs on behalf of others. Where they disagree is in a case where there is both land worth five sela coins that is liened property that had been previously sold to others and land worth five sela coins that is unsold property.

The Gemara explains the reasoning behind the dispute: Rabbi Yehuda maintains that a loan that is written in the Torah, i.e., a financial obligation by Torah law, such as redemption of the firstborn son with five sela coins, is considered as though it is written in a document, and it can therefore be collected from liened property, as can any loan recorded in a document. Therefore, the five sela coins that are liened property are available for one’s own redemption but not for that of one’s son, as the sale of the property presumably occurred before the birth of his firstborn. And therefore the priest goes and repossesses the land worth five sela that is liened property for his own redemption, like any debt written in a document; and with those five sela of unsold property he redeems his son. In this manner, one can fulfill both mitzvot.

And the Rabbis maintain: A loan that is written in the Torah is not considered as though it is written in a document, since buyers will not know to guard against repossession if it is not written in a document. Therefore, the five sela coins that are liened property are not available for redemption, and consequently his own mitzva is preferable. He accordingly redeems himself with the land that is not liened.

MISHNA: The five sela coins of the redemption of the firstborn son, with regard to which it is written: “Five shekels of silver, after the shekel of the Sanctuary” (Numbers 18:16), are calculated using a Tyrian maneh. The silver content of the Tyrian coinage is significantly higher than that of provincial coinage, which is worth one-eighth its value.

With regard to the thirty shekels paid to the owner of a Canaanite slave who is killed by an ox (see Exodus 21:32), and the fifty shekels paid by a rapist (see Deuteronomy 22:29) and by a seducer (see Exodus 22:16) of a young virgin woman, and the one hundred shekels paid by the defamer of his bride with the claim that she is not a virgin (see Deuteronomy 22:19), all of them, even those cases where the word shekel is not explicitly written, are paid in the shekel of the Sanctuary, whose value is twenty gera (see Numbers 18:16) and that is calculated using a Tyrian maneh. And all monetary obligations are redeemed, i.e., paid, with coins or with items of the equivalent value of money, except for the half-shekels that are donated to the Temple each year, which must be given specifically as coins.

GEMARA: The mishna stated that the five sela coins of the redemption of the son are calculated using a Tyrian maneh. In explanation of this, Rabbi Asi says: One must give five sela of the maneh used in Tyre. Rabbi Ami says: The five sela coins are equal to a golden Arabian dinar. Rabbi Ḥanina says: There is a Syrian sela [istera], eight of which are sold for a large golden dinar. One must give five of these for the redemption of the son.

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Bechorot 49b examines Rav and Shmuel's dispute over redeeming a firstborn son before thirty days, weighing whether the payment remains valid.