Exodus 34:22-24 (NET Bible) :
22 “You must observe the Feast of Weeks—the firstfruits of the harvest of wheat—and the Feast of Ingathering at the end of the year. 23 At three times in the year all your men must appear before the Sovereign Lord, the God of Israel. 24 For I will drive out the nations before you and enlarge your borders; no one will covet your land when you go up to appear before the Lord your God three times in the year.

Leviticus 23:15-22 (NET Bible) :
15 “‘You must count for yourselves seven weeks from the day after the Sabbath, from the day you bring the wave-offering sheaf; they must be complete weeks. 16 You must count 50 days—until the day after the seventh Sabbath—and then you must present a new grain offering to the Lord. 17 From the places where you live you must bring two loaves of bread for a wave offering; they must be made from two-tenths of an ephah of fine wheat flour, baked with yeast, as firstfruits to the Lord. 18 Along with the loaves of bread, you must also present seven flawless yearling lambs, one young bull, and two rams. They are to be a burnt offering to the Lord along with their grain offering and drink offerings, a gift of a soothing aroma to the Lord. 19 You must also offer one male goat for a sin offering and two yearling lambs for a peace-offering sacrifice, 20 and the priest is to wave them—the two lambs—along with the bread of the firstfruits, as a wave offering before the Lord; they will be holy to the Lord for the priest.

21 “‘On this very day you must proclaim an assembly; it is to be a holy assembly for you. You must not do any regular work. This is a perpetual statute in all the places where you live throughout your generations. 22 When you gather in the harvest of your land, you must not completely harvest the corner of your field, and you must not gather up the gleanings of your harvest. You must leave them for the poor and the resident foreigner. I am the Lord your God.’”

Number 28:26-31 (NET Bible) :
26 “‘Also, on the day of the firstfruits, when you bring a new grain offering to the Lord during your Feast of Weeks, you are to have a holy assembly. You must do no ordinary work. 27 But you must offer as the burnt offering, as a sweet aroma to the Lord, two young bulls, one ram, seven lambs one year old, 28 with their grain offering of finely ground flour mixed with olive oil: three-tenths of an ephah for each bull, two-tenths for the one ram, 29 with one-tenth for each of the seven lambs, 30 as well as one male goat to make an atonement for you. 31 You are to offer them with their drink offerings in addition to the continual burnt offering and its grain offering—they must be unblemished.

Deuteronomy 16:9-12 (NET Bible) :
9 You must count seven weeks; you must begin to count them from the time you begin to harvest the standing grain. 10 Then you are to celebrate the Feast of Weeks before the Lord your God with the voluntary offering that you will bring, in proportion to how he has blessed you. 11 You shall rejoice before him—you, your son, your daughter, your male and female slaves, the Levites in your villages, the resident foreigners, the orphans, and the widows among you—in the place where the Lord chooses to locate his name. 12 Furthermore, remember that you were a slave in Egypt, and so be careful to observe these statutes.

Acts 2:1-4 (NET Bible) :
Now when the day of Pentecost (Shavuot) had come, they were all together in one place. 2 Suddenly a sound like a violent wind blowing came from heaven and filled the entire house where they were sitting. 3 And tongues spreading out like a fire appeared to them and came to rest on each one of them. 4 All of them were filled with the Holy Spirit, and they began to speak in other languages as the Spirit enabled them.