Leviticus 23:

33 And Yahovah spake unto Moses, saying,

34 Speak unto the children of Israel, saying, The fifteenth day of this seventh month shall be the feast of tabbernacles for seven days unto Yahovah.


40 And ye shall take you on the first day the boughs of fruit trees, and branches of palm-trees, and the boughs of thick trees, and willows of the brook; and ye shall rejoice before Yahovah your Elohim seven days.

41 And ye shall keep it a feast unto Yahovah seven days in the year: it shall be a statute for ever in your generations; ye shall celebrate it in the seventh month.

42 Ye shall dwell in booths seven days; all that are Israelites born shall dwell in booths:

43 Thay your generations may know that I made the children of Israel to dwell in booths, when I brought them out of the land of Egypt: I am Yahovah your Elohim.

44. And Moses declared unto the children of Israel the feasts of Yahovah.

Leviticus 23:34-43 Demonstrates in The Feast of Tabernacles the True 7th day sabbaths. The first day of the feast, the 15th, and the eighth day of the feast, the 22nd, are both 7th day sabbaths. Dwelling in Booths for 7 days illustrates, the first day (of the week, the 16th, not the first day of the feast, the 15th) is the command to take boughs of goodly trees, and build a booth, on the 16th day, the first of the six working days, and on the 8th day of the feast, the last day and the 7th day sabbath, is the last day of dwelling in that booth, built on the first day (of the week).
This is a beautiful Truth, illustrating that the 7th day sabbaths are indeed timed by the moon, for He would not command all Israel, to build dwellings on the day that He said, "in it thou shalt not do any work". The false theory of unbreakable cycles of 7 from creation till now, would  sometimes have 7th day sabbaths falling on the 16th day of the moon, The first of the six working days, the beginning of dwelling in booths for seven days, the day commanded to build a booth to dwell in for the third quarter week of days.

Leviticus 23:33-44 And spoke Yahovah to Moses, saying, Speak to the sons of Israel, saying, In the fifteenth day of moon seventh this a feast of booths seven days to Yahovah: On the day first a gathering holy; any work of service not you shall do: Seven days you shall bring a fire offering to Yahovah; on the day eighth a gathering holy shall be to you and you shall bring near the fire offering to Yahovah; festive assembly it; any work of service not you shall do. These the set feasts of Yahovah which you shall proclaim them; gatherings holy to bring a fire offering to Yahovah, a burnt offering, and a food offering, a sacrifice and drink offerings, the thing of a day on its own day; besides the sabbaths of Yahovah, and besides your gifts, and besides all your vows, and besides all your free-will offerings which you shall give to Yahovah:
Leviticus 23:39 Only on the five ten day of the mo
on seventh, when you gather the increase of the land, shall you keep the feast of Yahovah seven days; on the day first a sabbath, and on the day eighth a sabbath. And you shall take to yourselves on the day first the fruit trees of majestic branches palm, and boughs of trees oak, and the willows of brook; and you shall rejoice before Yahovah your Elohim seven days: And you shall celebrate it a feast to Yahovah, seven days in a year, a statute never-ending for your generations; in the moon seventh you shall celebrate it in booths you shall live seven days all who are homeborn in Israel shall live in booths: So that may know your generations that in booths I caused to live the sons of Israel when I brought out them of the land of Egypt; I Yahovah your Elohim: And announced Moses the set feasts of Yahovah to the sons of Israel:

The following is an attempt to understand this scripture as it is hard to see why He would command man to take boughs of goodly trees and build a tabernacle on the shabat. There is stated that it is a feast of 7 days, yet is mentioned the first and the eighth day is a shabat. So I think the first day mentioned when we take boughs and branches of trees, that this may mean sawing or chopping to get them, is 1st day, of the six work days.
  At the beginning of this chapter it is commanded
Leviticus 23:3 "Six days is to be done work, and on the day seventh a sabbath of rest, a gathering holy; any work not you shall do; a sabbath it to Yahovah in all your dwellings:"
So following this logic it would seem that the 7 days of the feast, dwelling in booths, would begin on the "First" of the six days of work, and work began on the "First", to cut branches majestic and boughs to build a booth, and the last great day of the feast would end on the 7th day Sabbath, which is called the "eighth" day of the feast. So the first sabbath of this feast believers come together to worship Yahovah, and to speak of His Goodness, and fellowship and to be of one accord, see old friends, make new, and construction work begins with the start of the feast the following day. And the last great culminating day of the feast is the seventh day sabbath called the eighth day.
And you shall take to yourselves on the day first the fruit trees of majestic branches palm, and boughs of trees oak, and the willows of brook; and you shall rejoice before Yahovah your Elohim seven days:

1st day 13 bullocks, 2nd day 12 bullocks, 3rd day 11 bullocks, 4th day 10 bullocks, 5th day 9 bullocks, 6th day 8 bullocks, 7th day 7 bullocks, 8th day 1 bullock, see Numbers 29:12-36.

In the lunar calendar the first day of the moon is called the day of the new moon. And the eighth day of the moon is the first 7th day sabbath, as is similar in the feast of tabernacles, the last great day is the 7th day sabbath but called the eighth day of the feast.

2nd Chronicles 7:9, 10
And in the eighth day they made a solemn assembly: for they kept the dedication of the altar seven days, and the feast seven days. And on the three and twentieth day of the seventh moon he sent the people away into their tents, glad and merry in heart for the goodness that Yahovah had shewed unto David, and to Solomon, and to Israel His people.

1st Chronicles 29:17
Now they began on the first day of the first moon to sanctify, and on the eighth day (the sabbath) of the moon came they to the porch of Yahovah: so they sanctified the house of Yahovah, in eight days; and in the sixteenth day (next day after the sabbath 15th) of the first moon they made an end. (they kept the passover the next moon after cleaning and sanctifying the temple)

1st Kings 12:32 - an example of apostasy in rejecting the Divine Calendar, and keeping one's own appointed times.
And Jeroboam ordained a feast in the eighth moon, on the fifteenth day of the moon, like unto the feast that is in Judah...
33 So he offered upon the altar which he had made in Bethel the fifteenth day of the eight moon, even in the moon which he had devised of his own heart;*(The Christian Thanksgiving day) and ordained a feast unto the children of Israel: and he offered upon the altar, and burnt incense.

Nehemiah 8:14 And they found written in the law which Yahovah had commanded by Moses, that the children of Israel should dwell in booths in the feast of the seventh moon: 8:18 Also day by day, from the first day unto the last day, he read in the book of the law of Elohim. And they kept the feast seven days; and on the eighth day was a solemn assembly, according unto the manner.

Ezekiel 32:17
It came to pass also in the twelfth year, in the fifteenth day of the moon, that the word of Yahovah came unto me, saying.

More on the sabbaths in the feasts of Yahovah

Tabernacles is mentioned, future, in Zechariah 14:19.

The Seventh day shabat can only happen after six work days, or in a feast week, six week days, see Ezekiel 46:1

The Divine Credentials bears the Mark of "Absolute Perfection", less than this shows forth the manipulation of Scriptures by "the man of sin".

An email sent to a sister with quotes from Scripture and Ellen White intimating that the 4th commandment we have today, is different than what is inscribed on the tables of Stone, written by The Hand of our Heavenly Father.

Ezekiel 22:
8 Thou hast despised Mine holy things, and hast profaned My sabbaths.
26...and have hid their eyes from My sabbaths,

-PT- Advent Review and Sabbath Herald
-DT- 06-25-01
-AT- A Message to Be Borne
-PR- 13
Elohim has a message for the sinners in Zion, and the bearing of this
message is the work before Seventh-day Adventists. The warning must be given.
"Cry aloud, spare not, lift up thy voice like a trumpet." Be earnest and
decided. Make no concessions to transgressors. Bear the message to all
peoples, nations, and kindreds, telling them that Elohim has a law which is as
high above man-made laws as heaven is above the earth. Let not the truth
languish upon your lips. Let not your words be words of peace and safety. Say
not to the transgressors, It does not matter what you believe. Say to the
people, as Messiah said to Moses, "Six days may work be done; but in the
seventh is the Sabbath of rest, holy to Yahovah."