Sanhedrin 67B

מיתה אחת.

one type of death penalty, namely, decapitation. Since that is the only type of capital punishment that applies to non-Jews, it cannot be derived through a verbal analogy that the same type applies to a Jewish sorceror.

בן עזאי אומר: נאמר ״מכשפה לא תחיה״, ונאמר ״כל שכב עם בהמה מות יומת״. סמכו ענין לו, מה שוכב עם בהמה בסקילה ⁠– אף מכשף בסקילה.

The baraita continues: Ben Azzai says that it is stated: “You should not allow a witch to live” (Exodus 22:17), and it is stated in the following verse: “Whoever lies with an animal should be put to death” (Exodus 22:18). The fact that the Torah juxtaposes this matter to that matter is to teach that just as one who lies with an animal is executed by stoning (see Leviticus, chapter 20), so too, a warlock is executed by stoning.

אמר לו רבי יהודה: וכי מפני שסמכו ענין לו, נוציא לזה בסקילה? אלא, אוב וידעוני בכלל מכשפים היו, ולמה יצאו? להקיש עליהן ולומר לך: מה אוב וידעוני בסקילה ⁠– אף מכשף בסקילה.

With regard to this derivation, R' Yehuda said to him: And because the Torah juxtaposes this matter with that matter, should we take this person out to be stoned? Should he be sentenced to the most severe type of capital punishment on that basis? Rather, the source is as follows: A necromancer and a sorcerer were included in the general category of warlocks, and why were they singled out from the rest, with their prohibition and punishment stated independently? This was done in order to draw an analogy to them and say to you: Just as a necromancer and a sorcerer are executed by stoning, so too, a warlock is executed by stoning.

לרבי יהודה נמי, ליהוו אוב וידעוני שני כתובים הבאים כאחד, וכל שני כתובין הבאין כאחד אין מלמדין!

The Talmud asks: According to the opinion of R' Yehuda as well, let the punishment with regard to a necromancer and a sorcerer be considered two verses that come as one, i.e., that teach the same matter, and therefore the halakha of other cases cannot be derived from it, according to the principle that any two verses that come as one do not teach about other cases. In other words, if a halakha is taught with regard to two individual cases in the Torah, the understanding is that this halakha applies only to those cases. Had this halakha applied to all other relevant cases as well, it would not have been necessary for the Torah to teach it twice. The fact that two cases are mentioned indicates that they are the exceptions rather than the rule.