Exodus 16:23

Now on the sixth day when they were gathering a double quantity, two gomers for everyone, all the heads of the congregation came and told Moses, whereupon he said to them, Is not this what the Lord spoke, Sabbaths are a rest holy to the Lord? As for to-morrow, bake what you choose to bake and boil what you choose to boil and what is left lay up for to-morrow.

And Moses said to them, Is not this the word which the Lord spoke? To-morrow is the sabbath, a holy rest to the Lord: bake that ye will bake, and seethe that ye will seethe, and all that is over leave to be laid by for the morrow.