John Gill Commentary Exodus 35:1

"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." — Exodus 35:1 (ASV)

And Moses gathered all the congregation of the children of
Israel together
According to Jarchi, on the morrow after the day of atonement; that is, the next day after his descent from the mount, being desirous of setting about the building of the tabernacle, and making all things appertaining to it as soon as possible; which had been retarded through the sin of the golden calf, and making reconciliation for that:

and said unto them, these are the words which the Lord has
commanded, that you should do them ;
namely, the law of the sabbath, as it had a peculiar relation to the making of the tabernacle, and the freewill offerings to be made on that account; for as for the commands, or other ordinances, whether ceremonial or judicial, the people had been made acquainted with them before.