Punishment: Death Penalty for Desecrating the Sabbath Day
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Exodus 35:2
For six days work may be done, but the seventh day shall be your holy day, a Sabbath of complete rest to the LORD. Whoever does any work on that day must be put to death.
Numbers 15:32–36
While the Israelites were in the wilderness, a man was found gathering wood on the Sabbath day. / Those who found the man gathering wood brought him to Moses, Aaron, and the whole congregation, / and because it had not been declared what should be done to him, they placed him in custody.