Exodus 31:12-16

12And Yhwh spake unto Moses, saying, 13Speak thou also unto the children of Israel, saying, Verily my sabbaths ye shall keep: for it is a sign between me and you throughout your generations; that ye may know that I am Yhwh that doth sanctify you. 14Ye 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. 15Six days may work be done; but in the seventh is the sabbath of rest, holy to Yhwh: whosoever doeth any work in the sabbath day, he shall surely be put to death.1 16Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant.