Leviticus 23:15

And let seven full weeks be numbered from the day after the Sabbath, the day when you give the grain for the wave offering;

Exodus 34:22

And you are to keep the feast of weeks when you get in the first-fruits of the grain, and the feast at the turn of the year when you take in the produce of your fields.

Leviticus 23:10-11

Say to the children of Israel, When you have come to the land which I will give you, and have got in the grain from its fields, take some of the first-fruits of the grain to the priest;

Leviticus 25:8

And let seven Sabbaths of years be numbered to you, seven times seven years; even the days of seven Sabbaths of years, that is forty-nine years;

Deuteronomy 16:9-10

Let seven weeks be numbered from the first day when the grain is cut.

Numbers 28:26

And at the time of the first-fruits, when you give an offering of new meal to the Lord at your feast of weeks, there is to be a holy meeting: you may do no field-work:

Treasury of Scripture Knowledge

Summary

And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete:

Bible References

General references

Leviticus 23:10
Say to the children of Israel, When you have come to the land which I will give you, and have got in the grain from its fields, take some of the first-fruits of the grain to the priest;
Leviticus 25:8
And let seven Sabbaths of years be numbered to you, seven times seven years; even the days of seven Sabbaths of years, that is forty-nine years;
Exodus 34:22
And you are to keep the feast of weeks when you get in the first-fruits of the grain, and the feast at the turn of the year when you take in the produce of your fields.
Deuteronomy 16:9
Let seven weeks be numbered from the first day when the grain is cut.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain