Halakhah su I Re 18:28

That He prohibited us from making a laceration for the dead in our flesh, like the idol worshippers do. And this is His, may He be exalted, saying, "you shall not gash yourselves (titgodedu)" (Deuteronomy 14:1). And the prohibition about this was already repeated with His saying, "You shall not make any lacerations in your flesh for the dead" (Leviticus 19:28). And it has already been explained in the Gemara, Yevamot (Yevamot 13b), that the essence of the verse, "you shall not gash yourselves," is, you shall not make a wound. And there it also says, "'You shall not gash yourselves,' is required for itself, as [the Torah] is saying, 'Do not make a wound for a corpse." And in the Gemara, Makkot (Makkot 21a), they said, "A laceration and a gash are the same." And there it is explained [that] one who makes a gash for a corpse is liable whether it was [done] with the hand or with a tool; but for idolatry, one is liable with a tool, but by hand, one is exempt - as appears explicitly in prophecy, "and they gashed themselves according to their practice with knives" (I Kings 18:28). And they have already said (Yevamot 13b) that included in this is the prohibition of disunity in the religious practices of a city and division [into] groups. And they said, "'You shall not titgodedu' - you shall not make agudot, agudot (many groups)." But the essence of the verse is as we explained - do not make a wound for a corpse - whereas this is like a homily (drash). And likewise that which they said in Sanhedrin (Sanhedrin 110a) - "One who maintains a disagreement transgresses a negative commandment, as it is stated, 'and not be like Korach and his congregation' (Number 17:5)" - is also from a homiletic angle. However the essence of [that] verse is [simply] to deter [from this]. And according to what the Sages explained, it is surely a negation, not a prohibition. For they explained that the content of this statement is that God, may He be exalted, is saying that one who will disagree and challenge the priesthood at some future time will not be punished with that which Korach was punished. Indeed he will be [punished], "Like the Lord spoke through Moshe to him" - meaning, tzaraat - as that which He said to Moshe, "Place your hand in your bosom," (Exodus 4:6) and as is made clear with King Uzziah (II Chronicles 26). And I will [now] return to the [primary] intention of the commandment and say that the regulations of this commandment have already been explained at the end of Makkot and that one who transgresses this negative commandment is lashed. (See Parashat Re'eh; Mishneh Torah, Foreign Worship and Customs of the Nations 12.)

And there it explains that one who gashes in response to a death, whether by hand or with a utensil, is liable; [one who gashes] for idolatry, with a utensil is liable but by hand is exempt [from punishment], as comes from the explanation in the Navi, "And they gashed themselves like their manner with swords." (Melachim I 18:28).

To not gash ourselves, like the worshipers of idolatry: To not gash our bodies, like the worshipers of idolatry. And about this is it stated (Deuteronomy 14:1), "you shall not gash yourselves." And this negative commandment is repeated with another word, as it is stated (Leviticus 19:28), "And a marking for a soul, you shall not put onto your flesh, etc." And in Tractate Yevamot 13b, they, may their memory be blessed said, "'You shall not gash yourselves' is required for itself, as [the Torah] said that that you shall not make a wound." And it is also said there that "You shall not gash yourselves" is for the dead. And in Tractate Makkot 21a, they, may their memory be blessed, said that marking and gashing are one thing. And there it is said that one who makes a mark for the dead is liable whether it is with the hand or with a tool; but for idolatry, with a tool, [one is] liable, with the hand, [one is] exempt. As such was their custom to gash themselves in front of the idolatry with a tool, and like the matter that is written (I Kings 18:28), "and they gashed themselves like their statute with swords and spears." And regardless, according to that which appears [to come out] from the words of our Rabbis, may their memory be blessed, (Makkot 22) the liability of the negative commandment is only about one who gashes himself for the dead or for idolatry. But for one who gashes himself without a reason or from anger about his house that has fallen or his ship that has sunk - even though it is something extremely disgusting and ugly and forbidden - there is no liability of the negative commandment for it.