Shavuot - The Feast of Pentecost

Today (for me - in Australia) is the Feast of Shavuot, known in English as Pentecost.  Most probably celebrate it on a different date; see Feast Calendar and Yom Teruah - The Feast of Trumpets for an explanation of my calendar.  See also Does the Torah Still Apply? for why this feast wasn't done away with by Yeshua/Jesus.
The Biblical instructions for this feast are:

¹⁵ “You shall count seven full weeks from the day after the Sabbath, from the day that you brought the sheaf of the wave offering. ¹⁶ You shall count fifty days to the day after the seventh Sabbath. Then you shall present a grain offering of new grain to the Lord. ¹⁷ You shall bring from your dwelling places two loaves of bread to be waved, made of two tenths of an ephah. They shall be of fine flour, and they shall be baked with leaven, as firstfruits to the Lord. ¹⁸ And you shall present with the bread seven lambs a year old without blemish, and one bull from the herd and two rams. They shall be a burnt offering to the Lord, with their grain offering and their drink offerings, a food offering with a pleasing aroma to the Lord. ¹⁹ And you shall offer one male goat for a sin offering, and two male lambs a year old as a sacrifice of peace offerings. ²⁰ And the priest shall wave them with the bread of the firstfruits as a wave offering before the Lord, with the two lambs. They shall be holy to the Lord for the priest. ²¹ And you shall make a proclamation on the same day. You shall hold a holy convocation. You shall not do any ordinary work. It is a statute forever in all your dwelling places throughout your generations.  (Leviticus 23:15-21 ESV)

The "Sabbath" of verse 15 is the first weekly Sabbath in the Feast of Unleavened Bread.  The phrase "ordinary work", sometimes rendered "servile work", refers to any work.  The feast actually originated (in the physical realm) with Noah and the Flood:

And on the new moon of the third month he went forth from the ark, and built an altar on that mountain.  2. And he made atonement for the earth, and took a kid and made atonement by its blood for all the guilt of the earth; for everything that had been on it had been destroyed, save those that were in the ark with Noah. 3. And he placed the fat thereof on the altar, and he took an ox, and a goat, and a sheep and kids, and salt, and a turtle-dove, and the young of a dove, and placed a burnt sacrifice on the altar, and poured thereon an offering mingled with oil, and sprinkled wine and strewed frankincense over everything, and caused a goodly savour to arise, acceptable before the Lord. 4. And the Lord smelt the goodly savour, and He made a covenant with him that there should not be any more a flood to destroy the earth; that all the days of the earth seed-time and harvest should never cease; cold and heat, and summer and winter, and day and night should not change their order, nor cease for ever. 5. "And you, increase ye and multiply upon the earth, and become many upon it, and be a blessing upon it. The fear of you and the dread of you I shall inspire in everything that is on earth and in the sea. 6. And behold I have given unto you all beasts, and all winged things, and everything that moveth on the earth, and the fish in the waters, and all things for food; as the green herbs, I have given you all things to eat. 7. But flesh, with the life thereof, with the blood, ye shall not eat; for the life of all flesh is in the blood, lest your blood of your lives be required. At the hand of every man, at the hand of every (beast), shall I require the blood of man. 8. Whoso sheddeth man's blood by man shall his blood be shed; for in the image of God made He man. 9. And you, increase ye, and multiply on the earth." 10. And Noah and his sons swore that they would not eat any blood that was in any flesh, and he made a covenant before the Lord God for ever throughout all the generations of the earth in this month. 11. On this account He spake to thee that thou shouldst make a covenant with the children of Israel in this month upon the mountain with an oath, and that thou shouldst sprinkle blood upon them because of all the words of the covenant, which the Lord made with them for ever. 12. And this testimony is written concerning you that you should observe it continually, so that you should not eat on any day any blood of beasts or birds or cattle during all the days of the earth, and the man who eateth the blood of beast or of cattle or of birds during all the days of the earth, he and his seed shall be rooted out of the land. 13. And do thou command the children of Israel to eat no blood, so that their names and their seed may be before the Lord our God continually. 14. And for this law there is no limit of days, for it is for ever. They shall observe it throughout their generations, so that they may continue supplicating on your behalf with blood before the altar; every day and at the time of morning and evening they shall seek forgiveness on your behalf perpetually before the Lord that they may keep it and not be rooted out. 15 And He gave to Noah and his sons a sign that there should not again be a flood on the earth. 16. He set His bow in the cloud for a sign of the eternal covenant that there should not again be a flood on the earth to destroy it all the days of the earth. 17. For this reason it is ordained and written on the heavenly tables, that they should celebrate the feast of weeks in this month once a year, to renew the covenant every year. 18. And this whole festival was celebrated in heaven from the day of creation till the days of Noah-twenty-six jubilees and five weeks of years: and Noah and his sons observed it for seven jubilees and one week of years, till the day of Noah's death, and from the day of
Noah's death his sons did away with (it) until the days of Abraham, and they ate blood. 19. But Abraham observed it, and Isaac and Jacob and his children observed it up to thy days, and in thy days the children of Israel forgot it until ye celebrated it anew on this mountain. 20. And do thou command the children of Israel to observe this festival in all their generations for a commandment unto them: one day in the year in this month they shall celebrate the festival. 21. For it is the feast of weeks and the feast of first-fruits: this feast is twofold and of a double nature: according to what is written and engraven concerning it celebrate it. 22. For I have written in the book of the first law, in that which I have written for thee, that thou shouldst celebrate it in its season, one day in the year, and I explained to thee its sacrifices that the children of Israel should remember and should celebrate it throughout their generations in this month, one day in every year.  (Jubilees 6:1-22, Charles' translation)

In case you're unfamiliar with the Book of Jubilees, see The Canon of Scripture, Part 2: Enoch and Jubilees.  Pentecost is prominently mentioned in the Acts of the Apostles:

When the day of Pentecost arrived, they were all together in one place. ² And suddenly there came from heaven a sound like a mighty rushing wind, and it filled the entire house where they were sitting. ³ And divided tongues as of fire appeared to them and rested on each one of them. ⁴ And they were all filled with the Holy Spirit and began to speak in other tongues as the Spirit gave them utterance.

⁵ Now there were dwelling in Jerusalem Jews, devout men from every nation under heaven. ⁶ And at this sound the multitude came together, and they were bewildered, because each one was hearing them speak in his own language. ⁷ And they were amazed and astonished, saying, “Are not all these who are speaking Galileans? ⁸ And how is it that we hear, each of us in his own native language? ⁹ Parthians and Medes and Elamites and residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, ¹⁰ Phrygia and Pamphylia, Egypt and the parts of Libya belonging to Cyrene, and visitors from Rome, ¹¹ both Jews and proselytes, Cretans and Arabians—we hear them telling in our own tongues the mighty works of God.” ¹² And all were amazed and perplexed, saying to one another, “What does this mean?” ¹³ But others mocking said, “They are filled with new wine.”

Peter's Sermon at Pentecost

¹⁴ But Peter, standing with the eleven, lifted up his voice and addressed them: “Men of Judea and all who dwell in Jerusalem, let this be known to you, and give ear to my words. ¹⁵ For these people are not drunk, as you suppose, since it is only the third hour of the day. ¹⁶ But this is what was uttered through the prophet Joel:

¹⁷ “‘And in the last days it shall be, God declares,
that I will pour out my Spirit on all flesh,
and your sons and your daughters shall prophesy,
and your young men shall see visions,
and your old men shall dream dreams;
¹⁸ even on my male servants and female servants
in those days I will pour out my Spirit, and they shall prophesy.
¹⁹ And I will show wonders in the heavens above
and signs on the earth below,
blood, and fire, and vapor of smoke;
²⁰ the sun shall be turned to darkness
and the moon to blood,
before the day of the Lord comes, the great and magnificent day.
²¹ And it shall come to pass that everyone who calls upon the name of the Lord shall be saved.’

²² “Men of Israel, hear these words: Jesus of Nazareth, a man attested to you by God with mighty works and wonders and signs that God did through him in your midst, as you yourselves know— ²³ this Jesus, delivered up according to the definite plan and foreknowledge of God, you crucified and killed by the hands of lawless men. ²⁴ God raised him up, loosing the pangs of death, because it was not possible for him to be held by it. ²⁵ For David says concerning him,

“‘I saw the Lord always before me,
for he is at my right hand that I may not be shaken;
²⁶ therefore my heart was glad, and my tongue rejoiced;
my flesh also will dwell in hope.
²⁷ For you will not abandon my soul to Hades,
or let your Holy One see corruption.
²⁸ You have made known to me the paths of life;
you will make me full of gladness with your presence.’

²⁹ “Brothers, I may say to you with confidence about the patriarch David that he both died and was buried, and his tomb is with us to this day. ³⁰ Being therefore a prophet, and knowing that God had sworn with an oath to him that he would set one of his descendants on his throne, ³¹ he foresaw and spoke about the resurrection of the Christ, that he was not abandoned to Hades, nor did his flesh see corruption. ³² This Jesus God raised up, and of that we all are witnesses. ³³ Being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit, he has poured out this that you yourselves are seeing and hearing. ³⁴ For David did not ascend into the heavens, but he himself says,

“‘The Lord said to my Lord,
“Sit at my right hand,
³⁵ until I make your enemies your footstool.”’

³⁶ Let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified.”

³⁷ Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, “Brothers, what shall we do?” ³⁸ And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit. ³⁹ For the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to himself.” ⁴⁰ And with many other words he bore witness and continued to exhort them, saying, “Save yourselves from this crooked generation.” ⁴¹ So those who received his word were baptized, and there were added that day about three thousand souls. (Acts 2:1-41 ESV)

Clearly NOT done away with.  Have a happy Shavuot!