The Torah in Parashat Mishpatim (Shemot 21:20) addresses the case of somebody who fatally beats his Ebed Kena’ani (non-Jewish servant), and states, “Nakom Yinakem” – “He shall assuredly be avenged.” The Gemara in Masechet Sanhedrin understood this to mean that the man is executed by “Sayif” – the sword.
The Sefer Ha’hinuch lists as the 50th Biblical command the Misva for Bet Din to administer “Sayif” to those who are deserving of this form of capital punishment. Although the Torah introduces the punishment of “Sayif” specifically in the context of one who kills his servant, it applies to all cases of murder; the punishment for a person found guilty of murder is death by the sword. This form of execution is deemed less severe than Sekila (stoning) and Serefa (burning), but more severe than Henek (strangulation).
The Torah sentences a master to capital punishment for this crime, the Sefer Ha’hinuch explains, in order to help us eliminate feelings of cruelty. Although the Torah allows for the purchase of servants, who become the master’s property, nevertheless, the master must avoid cruelty, to the point that if he becomes so angry at his servant that he fatally strikes him, he is put to death.
There is a rule that when Bet Din convicts an offender to capital punishment, “Yad Ha’edim Tiheyeh Bo Ba’rishona” – the witnesses who testified about the crime begin the process of execution. In the case of Sekila, for example, the witnesses throw the first stones. The Ralbag (Rav Levi Ben Gershon, France, 1288-1344) explains that this was done to help ensure the accuracy of the witnesses’ testimony. Knowing that they will be participating in the execution, the witnesses are more likely to be deterred from presenting false or imprecise information, and will exercise greater care to speak accurately.
An exception is made in the case of murder, when instead of the witnesses, the victim’s family begins the execution. Another exception is a case where the witnesses do not have hands. The Torah commanded, “Yad Ha’edim Tihyeh Bo” – that the witnesses’ “hands” strike the convicted offender first, and therefore, if the witnesses do not have hands, the offender is not put to death.
After an offender receives “Sayif,” the knife used for the execution becomes forbidden for any sort of benefit, and it must be buried. It is not buried in the grave together with the offender, but is rather buried nearby.
Of course, Bet Din no longer has the authority to administer punishment. However, the Gemara teaches that even when Bet Din cannot punish sinners, Hashem arranges that willful sinners who do not repent will receive their due punishment in a manner similar to the way Bet Din would have punished them. This system is necessary in order to ensure compliance with the Misvot, and to allow us to create the just, stable, moral society that we are to create.