We have all heard and know of the importance of the number seven to Jews and its frequent use in scripture. Before studying its Hebrew origins I probably would have said Seven is a perfect and complete number and has spiritual importance. Sure, that's true. But it is of course deeper than that.
The reason Hebrew is so cool is because we learn about one word by studying all the other words that have the same root, and all the words can mean the same thing, but with slightly different meanings. The number Seven has LOTS of related words that share the same root. Here are some examples...
*The root word for seven (shebah), is the same for the word Sabbath (shebat), and satisfy (sabea), and swear (saba), and be complete (Shaba), and cease or rest (Shebat).
Each of those words have very strong relationships that go without the need for explanation, but I find the swearing aspect to fit less than the others. So if you say "I swear that I will...", you would literally be saying "I seven that I will..." Or, if you pledge allegiance to God or - "To the Flag", then you "Seven yourself to God". Or the pledge would say "I Seven myself to the flag of the United States of America..." But on the Sabbath, we swear ourselves, or make (renew) covenants with God.
So if we put it all together we could say something like this: "On the Sabbath Day, we rest from our labors, we are satisfied, feel complete, and swear ourselves to God".
Or here is what it would sound like to a Hebrew Person... "On the seventh day, we seven from our labors; we are seven'd, feel seven'd, and seven ourselves to God. No wonder Seven is so meaningful, and is the perfect number.
*The New Strong's Expanded Dictionary of the words in the Hebrew Bible; pg 270-271