Leviticus Chapter 23 Verse 15
"From the day after the Sabbath, the day you brought the sheaf of the wave offering, you are to count off seven full weeks. You shall count off fifty days until the day after the seventh Sabbath, and then present an offering of new grain to YaHuWaH."
The count of the 9 weeks leading up to Pentecost begins the day after the seventh weekly Sabbath following the first day of Unleavened Bread. In Hebrew it is called 'Shavuot'. It is celebrated on the day after the 9-week count, i.e., the 50th day. The word 'Pentecost' is a Greek word that derives from this count and means 'fiftieth'. It is also known as the 'Feast of Weeks' and the 'Feast of the Harvest'. Originally it is the time to present an offering of new grain from the summer wheat harvest to YaHuWaH to show joy and thankfulness for the harvest. It is an appointed time and a set-apart day where no work is to be done.
In a subsequent act of judgment over the rebellious people's sin of worshipping a pagan golden calf, 3,000 people died...
At this appointed time, we also see another amazing event. The Messiah Yahushua instructed his disciples to wait in Jerusalem after his crucifixion, resurrection, and ascension.
Luke Chapter 24 Verse 49
"And behold, I am sending the promise of my Father upon you. But stay in the city until you are clothed with power from on high."
Acts Chapter 2 Verse 1
"When the day of the Festival of Shavuot / Feast of Weeks had come, they were all with one mind in one place."
John Chapter 4 Verses 23 - 24
"But an hour is coming, and now is, when the true worshipers shall worship the Father in spirit and truth; for the Father also does seek such to worship Him. God is spirit, and those who worship Him need to worship in spirit and truth."
Shavuot, also known as the Feast of Weeks and Pentecost, is an appointed time for followers of the Messiah to fully commit to worshipping their heavenly Father in accordance with His Word in the Torah and led by His Spirit. Following this, we have the next appointed time: