Halakhah su Esodo 22:17

To not keep a witch alive: To not keep a witch alive. Rather, we kill her, as it is stated (Exodus 22:17), "You shall not keep a witch alive." And it is not specifically a witch, but rather anyone that does magic. It is just that it stated it according to what is common, as women are more involved with magic than men (Sanhedrin 67a).

To not soothsay: To not soothsay, as it is stated (Leviticus 19:26), "and you shall not soothsay (teonenu)." And the understanding of the matter is like they said in Sifra, Kedoshim, Chapter 6:2, that it is an expression of a time period (onah). [This] means to say that we do not fix time periods to say time x is good to do action y; and anyone who does it at that time will be successful, but one who does it at time z will not be successful - like the empty clairvoyants say. And the negative commandment about this matter is repeated in the Order of Shoftim, as it is written there (Deuteronomy 18:10), "There shall not be found in you, etc. a soothsayer." And they, may their memory be blessed, said (Sanhedrin 65b) that included in this negative commandment of the soothsayer is the fooling the eyes that people do. And this matter is a great type of machination that is connected with lightness of hand and its powerful quickness to the point that it appears to people that the trickster is doing fantastic things, meaning to say that they are supernatural. As what those that make efforts in this always do, such that they take a rope and put it into the corner of their clothes in front of people's eyes, and afterwards they take out a snake; and so [too,] they throw a ring into the air, and afterwards they take it out from the mouth of one of the bystanders in front of them; and many things similar to these. And each one of these evil acts is forbidden, and one who does it is called a fooler of the eyes. And it is included in the prohibition of the soothsayer and we administer lashes for it. And even though [the prohibition of the] soothsayer is stated next to the sorcerer in one verse, it is not precisely a type of magic. As if the prohibition about it was on account of the negative commandment of the sorcerer, we would not administer lashes for it, since the negative commandment of the sorcerer is given over to the warning of a death penalty from the court, as it is stated (Exodus 22:17), "You shall not keep a witch alive." And it is established for us (Eruvin 17b) that we do not administer lashes for any negative commandment that is given over to the warning of a death penalty from the court.

He prohibited us from keeping a sorcerer alive. And that is His saying, "You shall not keep a sorceress alive" (Exodus 22:17). And if we pardon him, we transgress a negative commandment - we do not only negate a positive commandment - and it is as if we pardoned one of those liable for one of the death penalties of the court. (See Parashat Mishpatim; Mishneh Torah, The Sanhedrin and the Penalties within their Jurisdiction 14.)

To not do magic: That we not make efforts with any act of magic at all. And about this is it stated (Deuteronomy 18:10), "There shall not be found in you, etc. or a sorcerer." And the content of magic is generally well-known to all - that people do machinations without end with types of grasses and stones, or [by] adhering things that people use, one to another. And some of them arrange these evil actions at certain known times or specific months that are fit for those crafts. And the Torah distances us with total distancing from all of these disgusting and ugly things, because they are vanities. And it is not fit for a holy people that holds the true religion to put their thought to these ugly things, but rather only to His service, may He be elevated. As He will fulfill every want of His people for the good, in their being sheltered by His great name, and their placing all of their trust and their reliance upon His kindnesses alone. And since these matters are very remote and ugly in front of Him, blessed be He, and there is a spark of matters of idolatry in them, He warned us about it with a negative commandment, and made liable for stoning anyone who makes efforts with this if it is volitional, and a fixed sin-offering if it is inadvertent. And it is also from the weightiness of the matter that Scripture warns the court not to forgive one who transgresses this, [more] than with other sins; and as it is stated (Exodus 22:17), "Do not keep alive a witch." And I have already spoken about the roots of this commandment on the negative commandment of "Do not keep alive a witch," in the Order of Veeleh HaMishpatim (Sefer HaChinukh 62).