Remember that you were a slave in the land of Egypt, and the HOLY ONE your God brought you out from there with a mighty hand and an outstretched arm; therefore the HOLY ONE your God commanded you to keep the sabbath day. Deuteronomy 5:15

Books, for instance, like "of the Bible"
Remember that you were a slave in the land of Egypt, and the HOLY ONE your God brought you out from there with a mighty hand and an outstretched arm; therefore the HOLY ONE your God commanded you to keep the sabbath day. Deuteronomy 5:15