Leviticus 23

1 ¶ And the LORD spake unto Moses, saying,
2 Speak unto the children of Israel, and say unto them, Concerning the feasts of the LORD, which ye shall proclaim to be holy convocations, even these are my feasts.
3 Six days shall work be done: but the seventh day is the sabbath of rest, an holy convocation; ye shall do no work therein: it is the sabbath of the LORD in all your dwellings.
This is a special day of the week, the seventh day, traditionally celebrated from sundown Friday to Sundown Saturday. It is a command not repeated in the list of commandments to Christians in Romans 13 because it was a sign to the Hebrews.

Exodus 31:13 Speak thou also unto the children of Israel, saying, Verily my sabbaths ye shall keep: for it is a sign between me and you throughout your generations; that ye may know that I am the LORD that doth sanctify you.

The Sabbath represents the seventh age, corresponding to the seventh day of creation, the Lord’s day of rest which will never end but even after the millennial reign of Christ will go on forever.

4 ¶ These are the feasts of the LORD, even holy convocations, which ye shall proclaim in their seasons.
5 In the fourteenth day of the first month at even is the LORD’S passover.
6 And on the fifteenth day of the same month is the feast of unleavened bread unto the LORD: seven days ye must eat unleavened bread.

Here is a distinction between Passover and the Feast of Unleavened Bread. But later the Jews will lump the entire celebration together, referring to it as Passover.

Luke 22:1 Now the feast of unleavened bread drew nigh, which is called the Passover.

7 In the first day ye shall have an holy convocation: ye shall do no servile work therein.
8 But ye shall offer an offering made by fire unto the LORD seven days: in the seventh day is an holy convocation: ye shall do no servile work therein.

So, there are two special days during this feast, the first and the last where no work is to be done.

9 And the LORD spake unto Moses, saying,
10 Speak unto the children of Israel, and say unto them, When ye be come into the land which I give unto you, and shall reap the harvest thereof, then ye shall bring a sheaf of the firstfruits of your harvest unto the priest:

1Corinthians 15:20 But now is Christ risen from the dead, and become the firstfruits of them that slept.

1Corinthians 15:23 But every man in his own order: Christ the firstfruits; afterward they that are Christ’s at his coming.

11 And he shall wave the sheaf before the LORD, to be accepted for you: on the morrow after the sabbath the priest shall wave it.
12 And ye shall offer that day when ye wave the sheaf an he lamb without blemish of the first year for a burnt offering unto the LORD.
Isaiah 53:7 He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.

13 And the meat offering thereof shall be two tenth deals of fine flour mingled with oil, an offering made by fire unto the LORD for a sweet savour: and the drink offering thereof shall be of wine, the fourth part of an hin.
14 And ye shall eat neither bread, nor parched corn, nor green ears, until the selfsame day that ye have brought an offering unto your God: it shall be a statute for ever throughout your generations in all your dwellings.
15 ¶ And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete:
16 Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the LORD.

I think, and I may have this wrong, but that this is Pentecost.

17 Ye shall bring out of your habitations two wave loaves of two tenth deals: they shall be of fine flour; they shall be baken with leaven; they are the firstfruits unto the LORD.
18 And ye shall offer with the bread seven lambs without blemish of the first year, and one young bullock, and two rams: they shall be for a burnt offering unto the LORD, with their meat offering, and their drink offerings, even an offering made by fire, of sweet savour unto the LORD.
19 Then ye shall sacrifice one kid of the goats for a sin offering, and two lambs of the first year for a sacrifice of peace offerings.
20 And the priest shall wave them with the bread of the firstfruits for a wave offering before the LORD, with the two lambs: they shall be holy to the LORD for the priest.
21 And ye shall proclaim on the selfsame day, that it may be an holy convocation unto you: ye shall do no servile work therein: it shall be a statute for ever in all your dwellings throughout your generations.
22 And when ye reap the harvest of your land, thou shalt not make clean riddance of the corners of thy field when thou reapest, neither shalt thou gather any gleaning of thy harvest: thou shalt leave them unto the poor, and to the stranger: I am the LORD your God.

The poor and foreigners were allowed to gather what was left over of any harvest. This was a type of welfare in the Hebrew Theocracy.

23 ¶ And the LORD spake unto Moses, saying,
24 Speak unto the children of Israel, saying, In the seventh month, in the first day of the month, shall ye have a sabbath, a memorial of blowing of trumpets, an holy convocation.
25 Ye shall do no servile work therein: but ye shall offer an offering made by fire unto the LORD.
26 And the LORD spake unto Moses, saying,
27 Also on the tenth day of this seventh month there shall be a day of atonement: it shall be an holy convocation unto you; and ye shall afflict your souls, and offer an offering made by fire unto the LORD.
28 And ye shall do no work in that same day: for it is a day of atonement, to make an atonement for you before the LORD your God.
29 For whatsoever soul it be that shall not be afflicted in that same day, he shall be cut off from among his people.
30 And whatsoever soul it be that doeth any work in that same day, the same soul will I destroy from among his people.

Verse 29, which is hard to understand, is then defined by verse 30, as is often the case. A person who is not afflicted with thoughts of his own sin and his separation from God on the day of atonement will work and ignore the sacredness of the day. Therefore, that person is to be killed. In fact, God will kill him.

31 Ye shall do no manner of work: it shall be a statute for ever throughout your generations in all your dwellings.
32 It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath.
33 ¶ And the LORD spake unto Moses, saying,
34 Speak unto the children of Israel, saying, The fifteenth day of this seventh month shall be the feast of tabernacles for seven days unto the LORD.
35 On the first day shall be an holy convocation: ye shall do no servile work therein.
36 Seven days ye shall offer an offering made by fire unto the LORD: on the eighth day shall be an holy convocation unto you; and ye shall offer an offering made by fire unto the LORD: it is a solemn assembly; and ye shall do no servile work therein.
37 These are the feasts of the LORD, which ye shall proclaim to be holy convocations, to offer an offering made by fire unto the LORD, a burnt offering, and a meat offering, a sacrifice, and drink offerings, every thing upon his day:
38 Beside the sabbaths of the LORD, and beside your gifts, and beside all your vows, and beside all your freewill offerings, which ye give unto the LORD.

As you can see, there are several Sabbaths and there are feast days. It’s important in understanding this to look at when Christ was crucified. For instance, who many Sabbaths were in that week.

39 Also in the fifteenth day of the seventh month, when ye have gathered in the fruit of the land, ye shall keep a feast unto the LORD seven days: on the first day shall be a sabbath, and on the eighth day shall be a sabbath.
40 And ye shall take you on the first day the boughs of goodly trees, branches of palm trees, and the boughs of thick trees, and willows of the brook; and ye shall rejoice before the LORD your God seven days.

John 12:13 Took branches of palm trees, and went forth to meet him, and cried, Hosanna: Blessed is the King of Israel that cometh in the name of the Lord.

Notice how they rejoiced before Jesus Christ, who is God the Son, or God in the flesh.

41 And ye shall keep it a feast unto the LORD 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 That 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 the LORD your God.
44 And Moses declared unto the children of Israel the feasts of the LORD.

I believe that the Jews still celebrate this holy day.