In Hebrew, all the letters have a numerical value, and adding the values of letters gives words a numerical value. For example, chai (life) is the number 18. Jews give gifts to charities in denominations of 18 to represent giving life.
It should not surprise us, then, that numbers in the Bible have significance, and what they mean is well-established and consistent. Whatever the number means in the first instance in Torah, that is what it means in prophesy and the New Testament.
The first instance of the number seven occurs in Genesis 2:
Thus heaven and earth and all their adornment were finished. And on the seventh day God finished the works He made, and He rested on the seventh day from all the works he made. Then God blessed the seventh day and sanctified it, because in it He rested from all His works God began to make.
(Genesis 2:1-3 OSB)
The main meaning associated with seven is finished, but it also connotes completeness, resting from works, blessing, and sanctification. Sanctification is an old word for setting one thing apart as holy, or not like all others. For example, in marriage, a man sets his wife apart from all other women, and she becomes holy to him. No other man is allowed to touch her because she has been sanctified to him in marriage.
Bear in mind then that seven = finished = complete = resting from works = blessing = holy. Every one of these words applies to the Church. We are a finished work in Jesus, one body (complete), delivered to rest from the works of the Law and the works of the flesh to walk in the Spirit, a blessed people that is Christ’s holy bride.
With this for background, let us consider a few of the many sevens we encounter in Bible study. In the Book of Daniel, weeks are sevens. The angel Gabriel declares:
Seventy weeks [lit. seventy sevens] are determined for your people and for your holy city to finish sin, to set an end to sin, to wipe out lawlessness, to atone for wrongdoings, to bring in everlasting righteousness, to seal up vision and prophesy, and to anoint the holy of Holies.
(Daniel 9:24 OSB)
The same words are here: seventy sevens; the holy city, finishing sin (the works of the flesh), setting an end to sin (completing it), anointing (by the Spirit) the holy of Holies – all the same meanings as the sabbath day of the Lord in Genesis.
Resting from our works is not just taking a day off to do our own pleasure. It is a day to atone for sin by confession, repentance, and communion, to stop doing what our flesh desires, and to remember that the Lord has set us apart as His bride to reflect his holiness.
The writer of Hebrews develops this theme in chapters 3 and 4:
And to whom did He swear that they would not enter His rest, but to those who did not obey? So we see that they could not enter in because of disbelief… for we who have believed do enter that rest, as He has said: ‘So I swore in My wrath, they shall not enter My rest,’ although the works were finished from the foundation of the world.
(Hebrews 3:18-4:3 OSB)
Clearly, in the Hebrew mind the concept of a day of rest is connected with deliverance from bondage, deliverance from the wilderness to the land of God’s promises, and deliverance from the works of the flesh and unbelief. We know what those works are:
Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God.
(Galatians 5:19-21)