Exodus 31:14-15

31:14 Ye shall keep the sabbath therefore; for it [is] holy unto you: every one that defileth it shall surely be put to death: for whosoever doeth [any] work therein, that soul shall be cut off from among his people. 31:15 Six days may work be done; but in the seventh [is] the sabbath of rest, holy to the LORD: whosoever doeth [any] work in the sabbath day, he shall surely be put to death.