Deuteronomy 25:2-3 "He shall give him forty lashes; he may not exceed"

Lashing is one of the punishments given by the Beit Din (See Positive Mitzvah 224).

The Torah sets a limit of thirty-nine lashes as the maximum amount a person may be given for any one sin.

The Torah also commands us to consider the age and health of the convicted person in order to determine how much pain he can endure.

This Negative Mitzvah forbids the judge to have more lashes or heavier lashes administered than the flogged person can bear.