Números 18:15 Referencias de la Mishná: Mishnah Bekhorot & Mishnah Eduyot

If one sets aside [a lamb] for the redemption of the first-birth of a donkey and it died: Rabbi Eliezer says: he is responsible as is the case with the five selas for the redemption of the first-born. But the sages say: he is not responsible, as is the case with the redemption of the second tithe. Rabbi Joshua and Rabbi Zadok testified concerning the redemption of the first-born of a donkey which died that the priest receives nothing [in such circumstances]. If the first-born of a donkey died [after the lamb for redemption had been set aside]: Rabbi Eliezer says: it shall be buried, but the lamb may be used. But the sages say: it does not need to be buried and the lamb belongs to the priest.

Rabbi Joshua and Rabbi Zadok testified concerning the redemption (lamb) of a firstborn donkey, that if it died, the priest receives nothing, Whereas Rabbi Eliezer says: the owner must bear the responsibility as with the five selas [in the case] of a [firstborn] son. But the Sages say: he bears no responsibility any more than in the case of the redemption of second tithes.

We must not redeem [a first-born] with slaves, nor with notes of indebtedness, nor with immovable properties, nor with objects of hekdesh. If one gives a written acknowledgment to a priest that he owes him five selas he is bound to give them to him, although his son is not considered as redeemed. Therefore, if the priest wishes to give him [the note of indebtedness] as a gift he is permitted to do so. If one set aside the redemption money of his son and it became lost, he is responsible for it, because it says: “Shall be for you [but] you shall surely redeem” (Numbers 18:15).