On the day of firstfruits, when you present an offering of new grain to the LORD during the Feast of Weeks, you are to hold a sacred assembly; you must not do any regular work.

Exodus 23:16
You are also to keep the Feast of Harvest with the firstfruits of the produce from what you sow in the field. And keep the Feast of Ingathering at the end of the year, when you gather your produce from the field.

Exodus 34:22
And you are to celebrate the Feast of Weeks with the firstfruits of the wheat harvest, and the Feast of Ingathering at the turn of the year.

Leviticus 23:15
From the day after the Sabbath, the day you brought the sheaf of the wave offering, you are to count off seven full weeks.

Leviticus 23:16
You shall count off fifty days until the day after the seventh Sabbath, and then present an offering of new grain to the LORD.

Numbers 28:18
On the first day there is to be a sacred assembly; you must not do any regular work.

Numbers 28:27
Present a burnt offering of two young bulls, one ram, and seven male lambs a year old as a pleasing aroma to the LORD,

Numbers 29:1
"On the first day of the seventh month, you are to hold a sacred assembly, and you must not do any regular work. This will be a day for you to sound the trumpets.

Deuteronomy 16:9
You are to count off seven weeks from the time you first put the sickle to the standing grain.

Also in the day of the first fruits, when you bring a new meat offering to the LORD, after your weeks be out, you shall have an holy convocation; you shall do no servile work: