Exodus 20:8

What is laid down here is not the institution of the sabbath rest, but its strict observance. The sabbath rest was known to the Babylonians before this time, and there are indications of its being previously known to the Israelites: see on Exodus 16:5. Hence, probably, the use of the word remember. To keep it holy] The seventh day is to be distinguished from other days (the root meaning of the word rendered 'hallow' is to separate: 'see on Leviticus 20:24), by abstinence from labour. Nothing is said here as to the religious observance of the day. But after the institution of the Levitical priesthood, the morning and evening sacrifices were doubled on the sabbath (see Numbers 28:9), and in later times the day was naturally that on which a 'holy convocation' was held: see Leviticus 23:3; Isaiah 66:23. After the exile, when synagogues were established, divine service was always celebrated on the sabbath.