There is an association in Hebrew, where seven is linked to the fulfillment of swearing. The Almighty is not slack in His choice of words. And David points out that, 'He has magnified His Word above all His Name.' Now there is something to meditate on before continuing.
Strong's is a concordance and not a lexicon in the classic sense. Nonetheless, it supplies a good basic grasp of the word 'seven' and it's uses and meanings.
The tri-literal root (Shin - Bet - Ayin) carries the three fundamental meanings of:
1) saba Fulfill, Satisfy or Complete
Strong’s H7649 שׂבע śâbêa‛ saw-bay'-ah
From H7646; satiated (in a pleasant or disagreeable sense): - full (of), satisfied (with).
2) sheba Seven
Strong’s H7651 שׁבעה שׁבע sheba‛ shib‛âh sheh'-bah, shib-aw'
From H7650; a primitive cardinal number; seven (as the sacred full one); also (adverbially) seven times; by implication a week; by extension an indefinite number: - (+ by) seven ([-fold], -s, [-teen, -teenth], -th, times). Compare H7658.
3) shaba Oath, Promise or Swearing
Strong’s H7650 שׁבע shâba‛ shaw-bah'
A primitive root; properly to be complete, but used only as a denominative from H7651; to seven oneself, that is, swear (as if by repeating a declaration seven times): - adjure, charge (by an oath, with an oath), feed to the full [by mistake for H7646], take an oath, X straitly, (cause to, make to) swear.
These words are found associated throughout scripture and ancient Hebrew writings. There relationship is illustrated in their usage. For example, the reason for seven angels with seven final plagues is explained in terms of fullness in the book of the Revelation:
Rev 15.1 And I saw another sign in heaven, great and marvellous, seven angels having the seven last plagues; for in them is filled up (or fulfilled) the wrath of God.
Also we find how the number seven is related to 'sware' and 'covenant' exemplified in Genesis 21:29-32.
Gen 21:29 And Abimelech said unto Abraham, What mean these seven ewe lambs which thou hast set by themselves?
Gen 21:30 And he said, For these seven ewe lambs shalt thou take of my hand, that they may be a witness unto me, that I have digged this well.
Gen 21:31 Wherefore he called that place Beersheba; because there they sware both of them.
Gen 21:32 Thus they made a covenant at Beersheba:
Abimelech and Abraham were in 'conflict resolution' mode in these passages. And Abraham, in his answer to Abimelech, was not asking, but telling Abimelech to take those sheep from him. They were to be slaughtered. They were to be used in a blood covenant that basically said that by taking those sheep, Abimelech was swearing that the well was dug by Abraham and was his. Remember the covenant that the Almighty made with Abraham and they walked between the pieces of the sacrifiesed animals? It was like that. And the violation of the terms of a blood covenant basically says that the person wronged could do to the violator of the covenant, what they had done together to the sheep. That is, cut them up in pieces. So this was serious stuff.
And what is transliterated as Beersheba in the KJV, is actually the (well) be’er of (swearing) shaba. Likewise throughout scripture, the swearings (covenants, promises, judgments, etc.) of our heavenly Father are fulfilled in His sevens.
You might want to Google 'blood covenant' and read the articles that relate to the ancient Semitic cultures for a fuller understanding of the practice. I hope this helps.
In His Love,