Leviticus 23:15
"'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.
Exodus 34:22
"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.
Leviticus 23:10-11
"Speak to the Israelites and tell them, 'When you enter the land that I am about to give to you and you gather in its harvest, then you must bring the sheaf of the first portion of your harvest to the priest,
Leviticus 25:8
"'You must count off seven weeks of years, seven times seven years, and the days of the seven weeks of years will amount to forty-nine years.
Deuteronomy 16:9-10
You must count seven weeks; you must begin to count them from the time you begin to harvest the standing grain.
Numbers 28:26
"'Also, on the day of the first fruits, 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.