Exodus 31:12-16

12And Jehovah spoke to Moses, saying,

13And thou, speak thou unto the children of Israel, saying, Surely my sabbaths shall ye keep; for this is a sign between me and you throughout your generations, that ye may know that it is I, Jehovah, who do hallow you.

14Keep the sabbath, therefore; for it is holy unto you; every one that profaneth it shall certainly be put to death: yea, whoever doeth work on it, that soul shall be cut off from among his peoples.

15Six days shall work be done; but on the seventh day is the sabbath of rest, holy to Jehovah: whoever doeth work on the sabbath day shall certainly be put to death.

16And the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations — [it is] an everlasting covenant.