The Torah commands in Parashat Korah (Bamidbar 18:15), “Ach Pado Tifdeh Et Bechor Ha’adam” – that one must redeem his firstborn son. This refers to a case where a woman’s first child is a boy, regardless of whether or not this child is the father’s firstborn. The Torah speaks here of a “Peter Rehem” – “first issue of the womb,” and thus this obligation applies when a woman’s first child is a boy.
This Misva, which is referred to as “Pidyon Ha’ben” – “the redemption of the son,” takes effect thirty days after the infant’s birth, when it has been ascertained that he is not a “Nefel” (child who dies soon after birth). The Torah requires performing the Pidyon from the time the child is thirty days old; it does not specify a time by which this obligation must be fulfilled. However, the Sefer Ha’hinuch writes that the Pidyon should be performed immediately after thirty days, without delay. This is, indeed, our practice – to perform the Misva immediately at the first opportunity, rather than delay it to a more convenient time like Sunday or a legal holiday.
The obligation of Pidyon Ha’ben rests upon the father. The mother does not bear the obligation to redeem her son, because firstborn women do not require a Pidyon Ha’ben after birth. If the father fails to redeem his son, it becomes the child’s obligation when he reaches the age of Bar Misva, though even then, the father can still redeem the child.
The redemption is done with an amount of money equivalent to five Sela’im, or with objects of value worth this amount. The Misva cannot be fulfilled by transferring real state, servants, or Shetarot (legal documents authorizing the collection of debts). This money may be divided among several Kohanim, such as by giving one Sela to five different Kohanim. As long as the tribe of Kohanim receives a total of five Sela’im, the obligation has been fulfilled.
The money must be paid to a Kohen; the Misva is not fulfilled if the money is given to a Kohen’s daughter.
The Kohen may return the money to the father after the Pidyon if he so wishes, as long as the father did not condition the payment from the outset on the Kohen’s returning it to him.
The Sefer Ha’hinuch here describes in detail the procedure for the Pidyon Ha’ben ceremony. He writes that a cup of wine and Hadasim are brought in honor of the event, and the Kohen recites the Berachot over the wine and over the fragrance of the Hadasim. The Sefer Ha’hinuch then proceeds to present the text of a Beracha which was customary for the Kohen to recite before the Pidyon. This Beracha does not appear in the Gemara, and was, apparently, instituted during the period of Geonim. We no longer have the custom to recite this Beracha, but it is nevertheless significant in that it gives us a sense of the meaning of this Misva and its underlying concepts. This Beracha reads as follows (for the Hebrew text, listen to audio recording):
Blessed are You, Hashem…who consecrated the fetus in his mother’s womb, and forty days [after conception] divided him into 248 limbs, and thereafter blew a soul within him, as it is written, “He blew within his nostrils” (Bereshit 2:7); He clothed him with skin and flesh, and covered him with bones and sinews, as it is written, “You clothe me in skin and flesh, and You cover me with bones and sinews” (Iyob 10:11); and He provided for him food and drink, honey and milk in which to delight, and appointed for him two ministering angels to guard him inside his mother’s womb, as it is written, “Life and kindness…” (Iyob 10:12). His mother says: This is my firstborn son, with whom the Almighty opened the doors of my belly. His father says: This is my firstborn son, and I am commanded to redeem him, as it says, “And every firstborn person among your children shall you redeem” (Shemot 13:13). May it be the will before You, Hashem my G-d, that just as You granted his father the privilege to redeem, so will You grant him the privilege [to raise him] to Torah, the wedding canopy, and good deeds. Blessed are You, who sanctifies the firstborn of Israel with regard to their redemption.
The father then recites the Beracha, “Asher Kideshanu Be’misvotav Ve’sivanu Al Pidyon Ha’ben,” followed by the Beracha of “She’hehiyanu.”
The Sefer Ha’hinuch cites a custom mentioned by the Ramban – which we follow today, as well – that the Kohen turns to the father and asks, “Which is dearer to you – your son, or these five Sela’im?” The father then responds, “My son is dearer to me.” (Of course, the father does not have a choice of whether or not to redeem his son; he bears a Torah obligation to perform the redemption.) The Kohen then takes the money from the father, places it over the father’s head, and proclaims, “This is in place of this; this is in exchange for this… This goes to the Kohen, and this child shall go to life, Torah, and fear of Heaven. May it be His will that just as he was brought to redemption, so shall he be brought to Torah, the wedding canopy, and good deeds; and let us say, ‘Amen’.”
After the Pidyon Ha’ben, the Kohen blesses the child with Birkat Kohanim.
This Misva applies in all places and at all times. As mentioned, it is binding only upon the father of a firstborn boy. This Misva does not apply if the father is a Kohen or a Levi, or if the mother is the daughter of a Kohen or a Levi.
If a father failed to redeem his firstborn son, and he died without doing so, then he has neglected this affirmative command.