Charles Ellicott Commentary 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." — Exodus 35:1-3 (ASV)

Moses, about to require the people to engage in the work—first, constructing the materials for the Tabernacle, and then erecting the Tabernacle itself—prefaced his requirements with a renewed proclamation of the law of the Sabbath, with greater detail and a new penalty. The necessity of such a re-proclamation had been indicated to him in the last commands he received before his first descent from Sinai (Exodus 31:12–17), and in doing so, he must be seen as carrying out those commands. The words recorded here are probably not all that he said to the people on the subject, but only some main points of his speech. He can hardly have omitted to tell them that the Sabbath was to be from then on a sign between God and His people (Exodus 31:17).