Exodus 35:2: "A sabbath rest to the Lord."
From Dr. John Murray as we rest today from our daily labor and are released to the contemplation of the glory of God:
God rested on the seventh day from his work of creation but he continued to be omnipresently active in the work of providence. Hence our rest of the Sabbath is not one of inaction, of idleness, far less of sloth. It is the rest of another kind of activity. It is indeed rest from the ordinary employments of the other six days. There is cessation from that activity and the labour which it entails. But it is also rest to or rest in; it is rest to and rest in the Lord.
That must mean the rest of activity in the specific worship of the Lord our God. There is a release from the labours of the six days, but it is also release to the contemplation of the glory of God. Cessation from the labours of the week must itself have its source and ground in obedience to God, and the gratitude which is both the motive and fruit of such obedience will minister to the worship which is the specific employment of the Sabbath rest. This is just saying that rest from weekly labours and the exercises of specific worship are inseparable and they mutually condition one another. In a Sabbath of rest to the Lord we cannot have the one without the other.
This is the sanctity of the Sabbath institution - it is the sanctity of separateness and it is the sanctity of concentrated adoration of the glory of the Lord our God.