Exodus 31:13-16

CLV(i) 13 Now you, speak to the sons of Israel saying, Surely, My sabbaths shall you keep, for it is a sign between Me and you throughout your generations to know that I, Yahweh, am hallowing you. 14 Hence you will keep the sabbath, for it is holy to you. Profaners of it shall be put to death, yea death, for if anyone is doing work in it, that soul will be cut off from among his people. 15 Six days shall work be done, and on the seventh day is a sabbath of cessation, holy to Yahweh. Everyone doing work on the sabbath day shall be put to death, yea death. 16 Hence the sons of Israel will keep the sabbath so as to make the sabbath an eonian covenant throughout their generations.