The Mekhilta DeRabbi Yishmael asks a deceptively simple question: what is the purpose of the commandment "You shall not bow down"? If the Torah already states in (Exodus 22:19) that "he who slaughters to a god shall be put to death — only to the Lord alone," why does the Torah also need a separate prohibition against bowing?
The answer lies in a fundamental distinction in Jewish law between punishment and warning. The verse about slaughtering to a god specifies the penalty — death. But Jewish law requires that before a person can be punished for a crime, there must be a prior exhortation, a formal warning embedded in the Torah itself. A person cannot be executed for an act unless the Torah first explicitly prohibits that act.
The verse "he who slaughters to a god shall be put to death" provides the punishment. But where is the exhortation — the prior warning? The Mekhilta finds it in "You shall not bow down to them" (Exodus 20:5). This commandment, from the Ten Commandments themselves, serves as the warning. It tells a person in advance: do not worship other gods. The later verse then provides the consequence: death.
This two-part structure — warning followed by penalty — is not optional in rabbinic jurisprudence. It is a procedural requirement. No one can be punished without having been warned. The Mekhilta's reading ensures that the Torah's legislation against idolatry contains both elements, perfectly paired. "You shall not bow down" warns. "He who slaughters to a god shall die" punishes. Together, they form a complete legal framework.