Exodus 16:23

And he said unto them, This is that which the Lord hath said (v. 5.), Tomorrow is the rest of the holy Sabbath unto the Lord, which up to that time had evidently not been observed. Bake that which ye will bake today, and seethe that ye will seethe; they were to prepare and eat their meals as usual; and that which remaineth over lay up for you to be kept until the morning, for use on the Sabbath-day.