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