Exodus 31
15 Ref Six days shall work be done, but on the seventh day is a sabbath of solemn rest, holy to Jehovah: whosoever doeth any work on the sabbath day, he shall surely be put to death.
16 Ref Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant.
17 Ref It is a sign between me and the children of Israel for ever: for in six days Jehovah made heaven and earth, and on the seventh day he rested, and was refreshed.