Original Verse:
Acts Chapter 2 Verse 1Now when the day of Pentecost had come, they were all with one accord in one place.

Reference Verses:
Numbers Chapter 28 Verse 26"'Also in the day of the first fruits, when you offer a new meal offering to Yahweh in your feast of weeks, you shall have a holy convocation; you shall do no servile work;
Leviticus Chapter 23 Verse 15-21 [15] "'You shall count from the next day after the Sabbath, from the day that you brought the sheaf of the wave offering; seven Sabbaths shall be completed: [16] even to the next day after the seventh Sabbath you shall number fifty days; and you shall offer a new meal offering to Yahweh. [17] You shall bring out of your habitations two loaves of bread for a wave offering made of two tenth parts of an ephah of fine flour. They shall be baked with yeast, for first fruits to Yahweh. [18] You shall present with the bread seven lambs without blemish a year old, one young bull, and two rams. They shall be a burnt offering to Yahweh, with their meal offering, and their drink offerings, even an offering made by fire, of a sweet aroma to Yahweh. [19] You shall offer one male goat for a sin offering, and two male lambs a year old for a sacrifice of peace offerings. [20] The priest shall wave them with the bread of the first fruits for a wave offering before Yahweh, with the two lambs. They shall be holy to Yahweh for the priest. [21] You shall make proclamation on the same day: there shall be a holy convocation to you; you shall do no regular work. This is a statute forever in all your dwellings throughout your generations.
Deuteronomy Chapter 16 Verse 9-11 [9] You shall count for yourselves seven weeks: from the time you begin to put the sickle to the standing grain you shall begin to number seven weeks. [10] You shall keep the feast of weeks to Yahweh your God with a tribute of a freewill offering of your hand, which you shall give, according as Yahweh your God blesses you: [11] and you shall rejoice before Yahweh your God, you, and your son, and your daughter, and your male servant, and your female servant, and the Levite who is within your gates, and the foreigner, and the fatherless, and the widow, who are in the midst of you, in the place which Yahweh your God shall choose, to cause his name to dwell there.
Acts Chapter 20 Verse 16For Paul had determined to sail past Ephesus, that he might not have to spend time in Asia; for he was hastening, if it were possible for him, to be in Jerusalem on the day of Pentecost.
1st Corinthians Chapter 16 Verse 8But I will stay at Ephesus until Pentecost,