Nehemiah 10:31,  see 33 also.
... that we would not buy it of them on the sabbath, or on the holy day:
(here we can see the new moon is called "the holy day". I was once of the opinion that the other lunar appointed times were not so important, but now I can see more clearly how important they are, since I now see the moon also appoints the weekly cycle with it's "four quarters" and four Seventh Rest Days. All Divine Appointments, Feast Days also, are all very important.)

Seeing Perfection builds confidence. Leviticus shows us that Tabernacles begins on a holy 7th day sabbath, lunar assignment the 15th, and ends on the 8th day, a holy 7th day sabbath, a solemn assembly, on the 22nd, see Lev. 23:36 & 39. Tabernacles is mentioned, future, in Zechariah 14:19. Adam and Eve dwelt in a garden, and here, with goodly boughs, in nature, His people dwell for 7 days, in the 7th month, similar to Adam and Eve. On the 1st day (weekly number assignment, not the 7th day weekly assigned day preceeding it, the 15th lunar assignment) they were to take boughs and build booths, working on the 1st of the 6 working days, and dwell in them that day and for the next 5 working days, and rest the 7th day sabbath in them, making a total of dwelling 7 days in booths.  This way of calculating, they didn't build booths, working on the 7th day sabbath.

Leviticus 23 ('yom' means 'day')

1. And spoke Yehovah to Moses, saying,
2. Speak to the sons of Israel, and you shall say to them, the set feasts of Yehovah, which you shall proclaim them gatherings; holy, These My set feasts.
3. Six yoms is to be done work, and on the yom seventh a sabbath of rest, a gathering holy; any work not you shall do; a sabbath it to Yehovah in all your dwellings.
4. These appointed times of Yehovah, gatherings holy which you shall proclaim them in their fixed times:
5. In the new moon, first, on fourteeth of new moon, between the evenings, the Passover to Yehovah;
6. And on the fifteenth yom of new moon, this, feast of unleavened bread to Yehovah; seven yoms unleavened bread you shall eat;
7. On the yom first a gathering holy shall be for you, any work of service not you shall do.
8. And you shall bring near a fire offering to Yehovah, seven yoms,   yom seventh, (of the weekly cycle, the seventh day after the six working days) a gathering holy any work of service not you shall do.

Exodus 12:18, 19
18. In the first, on the fourteenth yom of the new moon at even, ye shall eat unleavened bread, until the one and twentieth yom of the new moon at even.
19. Seven yoms shall there be no leaven found in your houses: for whosoever eateth that which is leavened, even that soul shall be cut off from the congregation of Israel, whether he be a stranger, or born in the land.

In the tenth day of the first moon, a lamb was selected and taken, at the time the Angel passed over Israel when he saw the blood on the doorpost.

In the tenth day of the 7th moon, was the day of atonement.

Unleavened bread is the same.   From the 14th at even until the 21st at even no leaven is to be eaten, or in the house. 7 days.

Verse 3 "Six yoms is to be done work, and on the yom seventh a sabbath of rest, a gathering holy; any work not you shall do a sabbath it to Yehovah in all your dwellings.

Verse 7 "On the yom first a gathering holy shall be for you, any work of service not you shall do."

Verse 8 "And you shall bring near a fire offering to Yehovah seven yoms; and the yom seventh a gathering holy, any work of service not you shall do."