Leviticus 23:15
And you shall count unto you from the day after the sabbath, from the day that you brought the sheaf of the wave offering; seven sabbaths shall be completed:
Exodus 34:22
And you shall observe the feast of weeks, of the first fruits of wheat harvest, and the feast of ingathering at the year's end.
Leviticus 23:10-11
Speak unto the children of Israel, and say unto them, When you are come into the land which I give unto you, and shall reap the harvest thereof, then you shall bring a sheaf of the first fruits of your harvest unto the priest:
Leviticus 25:8
And you shall number seven sabbaths of years unto you, seven times seven years; and the space of the seven sabbaths of years shall be unto you forty and nine years.
Deuteronomy 16:9-10
Seven weeks shall you number unto you: begin to number the seven weeks from such time as you begin to put the sickle to the grain.
Numbers 28:26
Also on the day of the first fruits, when you bring a new grain offering unto the LORD, at your Feast of Weeks, you shall have a holy convocation; you shall do no regular work: