Exodus 16:23 (CEV)
He [Moses] told them that the Lord had said, “Tomorrow is the Sabbath, a sacred day of rest in honor of me. So gather all you want to bake or boil, and make sure you save enough for tomorrow.”
God provided two gifts for his people as they headed into the wilderness: bread from heaven and Sabbath rest.
Life was hard in Egypt. Likely they served their masters every day. Weekly rest must have been as enticing as the mysterious manna.
God considered Sabbath rest so essential that he rearranged the laws of nature to make the bread from heaven last an extra day. 
