Exodus 31:16-18

American Standard Version

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 Jehovah made heaven and earth, and on the seventh day he rested, and was refreshed.

¹⁸ And he gave unto Moses, when he had made an end of communing with him upon mount Sinai, the two tables of the testimony, tables of stone, written with the finger of God.