A day that God claimed as His own
God did not recommend a day of rest. He appointed one, blessed it, and set it apart from the rest of the week. Then He put His own name on it. Scripture calls it the sabbath of the LORD thy God, which is a claim of ownership rather than a note of custom.
“Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: But the seventh day is the sabbath of the LORD thy God … For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.”
Exodus 20:8-11, KJV