The 45th prohibition is that we are forbidden from intentionally bruising ourselves, as the idol worshippers do.

The source of this commandment is G‑d's statement (exalted be He),1 "Do not mutilate yourselves (lo sis'godidu)." This prohibition is repeated in different words:2 "Do not make cuts in your skin for the dead."

It has been explained in the Talmudic tractate Yevamos3 that the verse, "Do not mutilate yourselves," is needed for itself4, i.e. to teach us that one may not mutilate oneself for someone who died.

Our Sages said in tractate Makkos5 that "s'rita"6 and "g'didah"7 are the same.8 There it is also explained that [for cutting oneself] for the dead, one incurs punishment whether done by hand or with an instrument. [If one cut oneself] for an idol, one incurs punishment only when done with an instrument, as is written in the Prophets,9 "They cut themselves with swords and spears, according to their custom." When done by hand, however, one is exempt.10

Our Sages11 said that this prohibition also includes not stating conflicting messages12 or having public disagreement. They said, "The phrase "lo sis'godidu" means not to make different groups (agudos)." This is like a drash13; the verse itself they explain as meaning that one may not mutilate oneself for someone who died.

So too their statement,14 "Anyone who carries on a dispute transgresses a prohibition, as it is written,15 'Do not be like Korach and his congregation,'" is also a type of drash. As our Sages explain, the verse itself is a warning and a negative statement, not a prohibition.16 Our Sages explained that G‑d notified that anyone in future generations who disagrees with [the status of] the Kohanim and claims it for himself will not meet the same fate as Korach and will not be punished by being swallowed up.17 His punishment will instead be,18 "As G‑d said to him through [literally, 'by the hand of'] Moses," i.e. tzora'as, as G‑d (exalted be He) told Moshe,19 "Place your hand on your chest [… and his hand was covered with tzora'as like snow]," and as is explained regarding Uzziah.20

To return to this prohibition, its details have been explained in the end of Makkos,21 and one who transgresses it is punished by lashes.