Moreover also I gave them my sabbaths, to be a sign between me and them, that they might know that I am the Lord that sanctify them. Ezekiel 20:12
(ML 259.1)
The Lord’s day mentioned by John was the Sabbath, the day on which Jehovah rested after the great work of creation, and which He blessed and sanctified because He had rested upon it. The Sabbath was as sacredly observed by John upon the Isle of Patmos as when he was among the people, preaching upon that day. By the barren rocks surrounding him, John was reminded of rocky Horeb, and how, when God spoke His law to the people there, He said, “Remember the sabbath day, to keep it holy.”
(ML 259.2)
The Son of God spoke to Moses from the mountaintop. God made the rocks His sanctuary. His temple was the everlasting hills. The Divine Legislator descended upon the rocky mountain to speak His law in the hearing of all the people, that they might be impressed by the grand and awful exhibition of His power and glory, and fear to transgress His commandments.... The law of Jehovah was unchangeable, and the tablets upon which He wrote that law were solid rock, signifying the immutability of His precepts. Rocky Horeb became a sacred spot to all who loved and revered the law of God.
(ML 259.3)
While John was contemplating the scenes of Horeb, the Spirit of Him who sanctified the seventh day, came upon him. He contemplated the sin of Adam in transgressing the divine law, and the fearful results of that transgression. The infinite love of God, in giving His Son to redeem a lost race, seemed too great for language to express. As he presents it in his epistle, he calls upon the church and the world to behold it.
(ML 259.4)
All who regard the Sabbath as a sign between them and God ... will represent the principles of His government. They will bring into daily practice the laws of His kingdom. Daily it will be their prayer that the sanctification of the Sabbath may rest upon them.
(ML 259.5)