וַאֲנִ֞י הִנֵּ֧ה לָקַ֣חְתִּי אֶת־הַלְוִיִּ֗ם מִתּוֹךְ֙ בְּנֵ֣י יִשְׂרָאֵ֔ל תַּ֧חַת כָּל־בְּכ֛וֹר פֶּ֥טֶר רֶ֖חֶם מִבְּנֵ֣י יִשְׂרָאֵ֑ל וְהָ֥יוּ לִ֖י הַלְוִיִּֽם׃
「看哪，我從以色列人中取了利未人，代替以色列人中所有頭胎出生的長子；利未人要歸我。
Siddur Sefard
This, my first born son, is the first issue of his mother's womb, and the Holy One, blessed is He has commanded to redeem him, as it is said: And those that are to be redeemed of them, from a month old shall you redeem them, according to your estimation, for the money of five silver shekalim, of the shekel of the Sanctuary which is equal to twenty geirah.1Numbers 18:16. And it is said: Sanctify unto me all the firstborn, whatsoever opens the womb among the Children of Israel, both of man and of beast is Mine.2Exodus 13:2.
Siddur Sefard
Which do you prefer, to give me your firstborn son who is the first issue of his mother's womb, or would you rather redeem him for five shekalim, as you are required to do by the Torah?