Exodus 35:1-3

And Moses assembled all the congregation of the children of Israel, and said unto them, These are the words which Jehovah hath commanded, that ye should do them. Six days shall work be done; but on the seventh day there shall be to you a holy day, a sabbath of solemn rest to Jehovah: whosoever doeth any work therein shall be put to death. Ye shall kindle no fire throughout your habitations upon the sabbath day.