God spoke to Moses:
"Tell the Israelites, 'Above all, keep my Sabbaths, the sign between me and you, generation after generation, to keep the knowledge alive that I am the God who makes you holy.
Keep the Sabbath; it's holy to you. Whoever profanes it will most certainly be put to death. Whoever works on it will be excommunicated from the people.
There are six days for work but the seventh day is Sabbath, pure rest, holy to God. Anyone who works on the Sabbath will most certainly be put to death.
The Israelites will keep the Sabbath, observe Sabbath-keeping down through the generations, as a standing covenant.
It's a fixed sign between me and the Israelites. Yes, because in six days God made the Heavens and the Earth and on the seventh day he stopped and took a long, deep breath.'"
When he finished speaking with him on Mount Sinai, he gave Moses two tablets of Testimony, slabs of stone, written with the finger of God.