(+ every) sabbath

Boyd’s Bible Dictionary:

(rest). Rest day, the seventh day of the week (Gen. 2:2-3). Under the Law given to Israel through Moses, it was to be kept as a day of rest (Ex. 16:23-30; 20:8-11; Lev. 19:3,30; 23:3; 25:4-9; Deut. 5:12-15). Day for consulting prophets (2 Kings 4:23). A day of teaching and joy (Neh. 8:1-12; Hos. 2:11). A whole week of time is implied (Matt. 28:1; Mark 16:1; Luke 24:1; John 20:1; Acts 20:7; 1 Cor. 16:2). The first-day of the week, the resurrection day of Christ, is called “the Lord’s Day” (John 20:26; Acts 20:6-11; 1 Cor. 16:2; Rev. 1:10).

Concise Bible Dictionary:

The first time the Sabbath is specifically mentioned in scripture is in Exodus 16:23, after the manna had been given from heaven; but the Sabbath clearly had its origin in the sanctification and blessing of the seventh day after the six days of creative work. And a hebdomadal division of days apparently existed up to the flood, since it is very distinctly mentioned in connection with Noah. We are also told in Mark 2:27 that the Sabbath was made for man. It was an institution which expressed God’s merciful consideration for man.
The words “rest” and “sabbath” in the passage in Exodus have no article, so that the sentence may be translated “Tomorrow is [a] rest, [a] holy Sabbath unto the Lord.” So in Exodus 16:25-26 there is no article: there is in Exodus 16:29. The Sabbath was soon after definitely enacted in the ten commandments (Ex. 20:8-11), and reference is there made to God having rested on the seventh day after the work of creation as the basis of the institution.
The Sabbath had a peculiar place in relation to Israel: thus in Leviticus 23, in the feasts of Jehovah, in the holy convocations, the Sabbath of Jehovah is first mentioned as showing the great intention of God. God had delivered Israel out of the slavery of Egypt, therefore God commanded them to keep the Sabbath (Deut. 5:15). The Sabbath was the sign of God’s covenant with them, and it may be that the Lord in repeatedly offending the Jews by (in their view) breaking the Sabbath by acts of mercy foreshadowed the approaching dissolution of the legal covenant (Ex. 31:13, 17; Ezek. 20:12,20). The Sabbath foreshadowed their being brought into the rest of God; but, because of the sin of those who started to go thither (who despised the promised land), God sware in His wrath that they should not enter into His rest (Psa. 95:11). God has purposed to bring His people into His rest, for whom there remains therefore the keeping of a Sabbath (Heb. 4:9).
The Sabbath was never given to the nations in the same way as to Israel, and amid all the sins enumerated against the Gentiles, we do not find Sabbath-breaking ever mentioned. Nevertheless, it appears to be a principle of God’s government of the earth that man and beast should have one day in seven as a respite from labor, all needing it physically.
The Christian’s Sabbath is designated the LORD’S DAY—and is as distinct in principle from the Jewish legal Sabbath as the opening, or first day of a new week is from the close of a past one. The Lord lay in death on the Jewish Sabbath: the Christian keeps the first day of the week, the resurrection day. See LORD’S DAY.

Strong’s Dictionary of Hebrew Words:

intensive from 7673; intermission, i.e (specifically) the Sabbath
KJV Usage:
(+ every) sabbath