The Greek terms which are translated “Lord’s day” in Revelation 1:10, are kuriake hemera. The first of these terms signifies simply lordly, or belonging to the Lord, and the second means simply day. These two words, as used in Revelation 1:10, signify lordly day, or day belonging to the Lord, or Lord’s day. Revelation 1:10 does not say that the first day is the Lord’s day, or that the seventh day is the Lord’s day. Other scriptures must therefore decide which day is the Lord’s day.RFOS 79.3

Because the term kuriake (lordly) is found only in another passage in the Greek New Testament (1 Corinthians 11:20), and because in that passage it is applied to the Lord’s supper, some will claim that the “Lord’s day” of Revelation 1:10 must be a day that belongs to the Lord Jesus. It would not be against the Sabbath cause even to admit that the Lord’s day mentioned in Revelation 1:10 is the day of Christ; for the seventh day (not the first) is the day of which Christ is Lord, and is, in a certain sense, the day of the Lord Jesus. It is the Sabbath that he observed, and that he took so much pains to teach, wrenching it from the thralldom of the Jews. Christ was one with the Father in the creation of the world (Genesis 1:26; John 1:3; Ephesians 3:9; Hebrews 1:2), and it would be unreasonable to believe that he was not interested in the institution which commemorates the great work of creation in which he had taken part.RFOS 79.4

But is it necessary to apply the term kuriake, in Revelation 1:10, only to Christ? Does the genius of the Greek language require that we do this?-By no means. In Greek, as well as in the English, lordly may be applied to other things than to those which belong to Christ. But there is a principle which is true in all languages, and which permits us to apply the term in question to Jehovah; namely, that the sense of an adjective or qualifying word which is derived from a substantive, must be determined by the aid of that substantive. Take, for example, the words office and official. The official duties of a person are the duties which grow out of his office. Let us apply this principle to the case before us. We have kuriake (lordly) which is derived from kurios (Lord), and kurios is applied in the original to God the Father as well as to Christ. David, speaking of Jehovah and of Christ, says, “The Lord [kurios the Father] said unto my Lord [kurio, the Son; it is the same noun as the first, only it is in a different case], Sit thou on my right hand, till I make thine enemies thy footstool.” Matthew 22:44. Other texts could be quoted in support of this point.RFOS 80.1

As there is but one Lord's day, and as the Lord claims the seventh day, and not the first, as his own, it is the seventh day that is the Lord’s day. “The seventh day,” says the Lord of lords, “is the Sabbath of the Lord thy God: in it thou shalt not do any work.” Exodus 20:10. See also Isaiah 58:13.RFOS 80.2

Therefore, whether the term Lord in Revelation 1:10 be applied to Christ or to Jehovah, the seventh day is the Lord’s day.RFOS 81.1

THE ROYAL LAW OF LIBERTY

THE SABBATH BETWEEN, OR THE MARGINAL READING OF Acts 13:42