Leviticus 24:19

And if a man cause a blemish in his neighbour; as he hath done, so shall it be done to him;

The verse stands in Leviticus 24:10-25, which records the first stoning to death, imposed for blasphemy.
It requires that a man who causes a blemish or injury in his neighbour have the same done to him, a strict injury-for-injury rule standing alongside life for life.
The penalty is proportionate to the harm done, not a license for uncontrolled revenge.

In the case of murder, the murdered person's nearest kinsman, the Go'el, was responsible for exacting the penalty by killing the murderer, with no civil officer carrying out the execution.
The surrounding law commands death for blasphemy and murder, showing that Sabbath-breaking was punished with the same death penalty as murder, blasphemy, idolatry, disobedience to parents, covetousness and theft, which are moral offenses.
Causing such injury to another brings the transgressor under the law's curse, as an example of breaking the third commandment.