Exodus 31:15-17

King James Version

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.

¹⁶ Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant.

¹⁷ It is a sign between me and the children of Israel for ever: for in six days the Lord made heaven and earth, and on the seventh day he rested, and was refreshed.