Commentaire sur L’Exode 13:2

פטר כל רחם THE FIRST OFFSPRING OF EVERY WOMB — The words mean: that which first openeth the womb, the root פטר meaning to open, as in (Proverbs 17:14) “As one makes an opening (פוטר) for water so is the beginning of strife”; and so, too, is (Psalms 22:8) יפטירו בשפה i. e. “they open the lips”.

SANCTIFY UNTO ME. This means that they are to consecrate the firstborn at once so that the commandment be applicable in the wilderness. This chapter adds many commandments: that they remember the day [when they left Egypt] and that the month was Aviv,³⁶⁴Verses 3-4. and that they keep this ordinance in its season.³⁶⁵Verse 10. This is an allusion to the intercalation [of an extra month] in the lunar year,³⁶⁶A lunar year — i.e., twelve lunar months — totals 354 days, 8 hours, 48 minutes and 36 seconds, as opposed to the solar year, which consists of 365 days, 6 hours and 48 seconds (Mishneh Torah, Z’manim, Hilchoth Kiddush Hachodesh, 9:2). There is a difference of nearly eleven days, and in order to exclude the possibility of the Passover being shifted from the spring, it is therefore necessary to interpolate an additional month about once every three years. since we are to observe the Passover only in the month of Aviv, [which is the spring]. On the subject of leavened bread, this chapter adds: Neither shall there be leaven seen with thee, in all thy borders.³⁶⁷Verse 7. At the conclusion, it adds the commandment of the frontlets.³⁶⁸Verse 16.

קדש לי כל בכור, they all have to be redeemed just as other sanctified items which cannot be used for their designated purpose can be redeemed; otherwise they are forbidden for secular use. This prohibition is spelled out in Deuteronomy 15,19 in the words לא תעבוד בבכור שורך, “you are not allowed to perform work with your firstborn ox.” The amount designated here by the Torah for redeeming a human being is the minimum applicable mentioned in connection with this legislation in chapter 27 in Leviticus. Whereas a fully mature male over 20 is valued at 50 shekel, the 30 day old infant is valued at 5 shekel.