(34) Say to the Israelite people: On the fifteenth day of this seventh month there shall be the Feast of Sukkot to ה׳, [to last] seven days. (35) The first day shall be a sacred occasion: you shall not work at your occupations; (36) seven days you shall bring offerings by fire to ה׳.

On the eighth day you shall observe a sacred occasion and bring an offering by fire to ה׳; it is a solemn gathering: you shall not work at your occupations.

(10) Such shall be the covenant between Me and you and your offspring to follow which you shall keep: every male among you shall be circumcised. (11) You shall circumcise the flesh of your foreskin, and that shall be the sign of the covenant between Me and you. (12) And throughout the generations, every male among you shall be circumcised at the age of eight days...

(1)ה׳ spoke to Moses, saying: (2) Speak to the Israelite people thus: When a woman at childbirth bears a male, she shall be impure seven days; she shall be impure as at the time of her condition of menstrual separation.— (3) On the eighth day the flesh of his foreskin shall be circumcised.—

(27) When an ox or a sheep or a goat is born, it shall stay seven days with its mother, and from the eighth day on it shall be acceptable as an offering by fire to ה׳.

(1) On the eighth day Moses called Aaron and his sons, and the elders of Israel.

כלות משה להקים [AND IT CAME TO PASS ON THE DAY] THAT MOSES HAD FINISHED SETTING UP [THE TABERNACLE] — but it is not said, “on the day Moses set up”; this (the phrase כלות … להקים, “had finished setting up”) teaches us that during each of the seven days of installation Moses used to erect and dismantle it (the Tabernacle), but on that day (the eighth) he erected it but did not again dismantle it; for this reason it is said: “on the day that (Moses) finished setting up” — i.e. on that day his repeated construction and deconstruction of it came to an end. (Sifrei Bamidbar 44).

(1)חכמות בנתה ביתה חצבה עמודיה שבעה. טבחה טבחה מסכה יינה אף ערכה שלחנה. שלחה נערותיה תקרא, על גפי מרמי קרת., “Wisdom has built her house, when she has hewn seven pillars. She has slaughtered the meat, mixed her wine; she has also set her table. She has sent out her maids, she cries out from the highest places in the town.” (Proverbs 9,1-3).

(4) This Midrash (Midrash Mishley chapter 9) interpreted the word שבעה, “seven,” which Solomon mentioned in verse one literally.

The reason is that the number seven has equal significance in the celestial regions and the terrestrial regions. There are many commandments in the Torah where the number “seven” plays a significant role.

The Sabbath is the seventh day;
the Jubilee year is the conclusion of seven cycles of seven years, shmita שמטה.
Both the festival of Passover and Tabernacles consist of seven days.
The components of the four species of plants used on the festival of Sukkot total seven, (1 lulav, 1 etrog, 2 willow-branches, and 3 branches of the myrtle).
We observe a period of seven days of mourning for close relatives who have died; we observe seven days of celebration when a couple get married.

The common denominator of all these commandments or practices involving the number seven is that they somehow symbolise the seven days in which G’d created and completed the universe.

Even a Gentile prophet such as Bilam built seven altars for G’d before embarking on his nefarious scheme of cursing the Jewish people (which was thwarted by G’d). He told G’d specifically that he had erected seven altars (Numbers 23,4).

It is not surprising therefore that there were seven days of inauguration for the Tabernacle. G’d Himself referred to them as such (Leviticus 8,33). The spiritual origin of these rites involving the number seven is one and the same.

If Aaron did not get consecrated on the seventh day itself but only on the morrow, the eighth day, this was because of the special nature of performing service in the Sanctuary of the Lord. Seeing G’d is essentially “One,” this is symbolized by the fact that Aaron did not commence his duties until the “first” day after the seven days of his consecration, i.e. the day of the “One.”

(5) ויהי ביום השמיני קרא משה לאהרן ולבניו ולזקני ישראל , “It was on the eighth day; Moses called upon Aaron, his sons, and the elders of Israel.” The reason that the office of the High Priest began functioning on the eighth day was due to yet another cause in addition to what we have mentioned.

We observe that in connection with the Tabernacle and the Temple the number eight plays a very significant role.

The High Priest wore eight garments.

The number of fragrances constituting the anointing oil and incense was eight. The anointing oil contained four such fragrances, i.e. מר, קנמון, קנה, קדה, (Exodus 30,23-24) whereas there were four additional fragrances which made up the incense. They were נטף, שחלת, חלבנה, לבונה (30,34).

The number of staves used to carry the furnishings of the Tabernacle also amounted to eight; 2 each for the Holy Ark, 2 for the golden [incense] Altar, 2 for the table, and two for transporting the copper [animal sacrifice] Altar.

Animals which were basically fit as sacrifices on the Altar had to be at least eight days old (Leviticus 22,27).

The musical instruments [or types of psalm?] used when the Levites sang the daily hymn during the service numbered eight as we know from Psalms 4,1 and others: lamnatzeach, al neginot, al machalat, al alamot, al hanchilut, al shoshanim, al ha'gitit, al ha'shminit.

(Note: the last of these "al ha'shminit" means "on the eighth." Eight-stringed instrument? Eight-noted scale?)

In this instance the eighth day was the first day of Nissan, a day when the Tabernacle was not only erected but remained standing. The day was distinguished with “ten crowns” in the language of our sages (Rashi). In other words, it was distinguished, honored in ten different ways. 1) It was the beginning of the second year since the Exodus. 2) It was the first day on which Aaron functioned as High Priest. 3) It was the first day on which sacrifices were offered in the Tabernacle. 4) It was the first time the people of Israel received the priestly blessings. 5) It was the first day on which heavenly fire descended onto the copper altar. 6) It was the first time the male goat of the New Moon offering was ever offered. 7) It was the first time that animals which had been slaughtered without previously having been designated as a sacrifice were no longer permitted to be eaten. 8) It was the first day when the Shechinah took up residence on earth. 9) It was the first of the twelve days on which the princes offered their respective offerings. Nachshon ben Aminadav, prince of the tribe of Yehudah, was the first to offer same. 10) It was the first day on which people who had contracted certain types of ritual impurity had to leave the camp, i.e. a testimony to the sanctity of the encampment of the whole people.
We find a similar description in Torat Kohanim describing the day as “taking” ten crowns, i.e. it was first in order of the creation. [There are two views as to whether the world was created (completed) on the first of Tishrey or the first of Nissan; this is the latter view. Ed.].

Now, sometimes this Sefirah [Binah] is called the Jubilee: Yovel-יובל, for as we have already explained, all manner of freedom and redemption depend on this Sefirah.

The reason being that all seven lower sefirot are sometimes affected by the mistakes of the lower beings, God forbid, such that they are in a state that is as if there is a cessation of beneficence. ... Therefore, when people sin below, the Sefirah of Understanding-Binah, as it were diminishes the range of her blessings, and it is then as though the other Sefirot must traverse various paths until they are gathered to ascend to the Sefirah of Understanding-Binah, which causes that those below remain in a state of destruction.

However, when the lower Sefirot are attached to the Sefirah of the Jubilee-Yovel-יובל, and draw her beneficence and blessings downwards, then all kinds of freedom and redemption are found in all the Sefirot, and in all beings that are sustained and provided for by the Sefirah of Kingship-Malchut, that receives the flow of blessing from them.

And know that a future time will come in which the righteous folks will ascend until they attach themselves to the Sefirah of Understanding-Binah, which is the mystery of the World-That-Is-Coming (Olam Haba-עולם הבא), and they will go forth into freedom and be redeemed from every kind of destruction and suffering, according to the secret of the verse, “Who redeems your life from destruction.” (Ps 103:4)

...

In this manner I will give you hints and if you merit, contemplate their primary root:

The secret of Understanding-Binah-בינה is called the Jubilee-Yovel-יובל, since through her everything will go forth to freedom.

All who merit to adhere to her will never see worry or any lack, since She adheres to the innermost chambers of the upper sefirot, where there is no worry or no lack whatsoever...

Whoever adheres to the Jubilee-Yovel-יובל is himself redeemed, since there is nothing, neither minister, nor angel, nor anything in the world surrounding the Jubilee-Yovel-יובל that can cause any damage whatsoever. It rather is solely the world of mercy-Rachamim.

§ It is taught in a baraita: They said about Rabban Shimon ben Gamliel that when he would rejoice at the Celebration of the Place of the Drawing of the Water on Sukkot, he would take eight flaming torches and toss one and catch another, juggling them, and, though all were in the air at the same time, they would not touch each other. …

GEMARA:Rav Ḥanan bar Rava says: When are these festivals celebrated? Kalenda is celebrated during the eight days after the winter solstice, and Saturnalia is celebrated during the eight days before the winter solstice. … With regard to the dates of these festivals, the Sages taught: When Adam the first man saw that the day was progressively diminishing, as the days become shorter from the autumnal equinox until the winter solstice, he did not yet know that this is a normal phenomenon, and therefore he said: Woe is me; perhaps because I sinned the world is becoming dark around me and will ultimately return to the primordial state of chaos and disorder. And this is the death that was sentenced upon me from Heaven, as it is written: “And to dust shall you return” (Genesis 3:19). He arose and spent eight days in fasting and in prayer. Once he saw that the season of Tevet, i.e., the winter solstice, had arrived, and saw that the day was progressively lengthening after the solstice, he said: Clearly, the days become shorter and then longer, and this is the order of the world. He went and observed a festival for eight days. Upon the next year, he observed both these eight days on which he had fasted on the previous year, and these eight days of his celebration, as days of festivities. He, Adam, established these festivals for the sake of Heaven, but they, the gentiles of later generations, established them for the sake of idol worship.