Treasury of Scripture Knowledge
Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the corn.
And thou shall keep the feast of weeks to LORD thy God with a tribute of a freewill-offering from thy hand, which thou shall give, according as LORD thy God blesses thee.
and the feast of harvest, the first-fruits of thy labors, which thou sow in the field, and the feast of ingathering at the end of the year, when thou gather in thy labors out of the field.
And thou shall observe the feast of weeks, [even] of the first-fruits of wheat harvest, and the feast of ingathering at the year's end.
And ye shall count to you from the morrow after the Sabbath, from the day that ye brought the sheaf of the wave-offering, there shall be complete seven Sabbaths.
Also in the day of the first-fruits, when ye offer a new meal-offering to LORD in your [feast of] weeks, ye shall have a holy convocation. Ye shall do no servile work.
2 Chronicles 8:13
even as the duty of every day required, offering according to the commandment of Moses, on the Sabbaths, and on the new moons, and on the set feasts, three times in the year, [even] in the feast of unleavened bread, and in the feas
And while fulfilling the day of Pentecost, they were all together at the same place.
1 Corinthians 16:8
But I will remain at Ephesus until Pentecost.
Because of this we ought to give more earnest heed to the things that were heard, lest we might slip away.