Leviticus 23:10-15

10“Speak to the Israelites and say to them: ‘When you enter the land I am going to give you and you reap its harvest, bring to the priest a sheaf of the first grain you harvest. 11He is to wave the sheaf before the LORD so it will be accepted on your behalf; the priest is to wave it on the day after the Sabbath. 12On the day you wave the sheaf, you must sacrifice as a burnt offering to the LORD a lamb a year old without defect, 13together with its grain offering of two-tenths of an ephah That is, probably about 7 pounds or about 3.2 kilograms; also in verse 17 of the finest flour mixed with olive oil—a food offering presented to the LORD, a pleasing aroma—and its drink offering of a quarter of a hin That is, about 1 quart or about 1 liter of wine.

14You must not eat any bread, or roasted or new grain, until the very day you bring this offering to your God. This is to be a lasting ordinance for the generations to come, wherever you live.

The Festival of Weeks 15“ ‘From the day after the Sabbath, the day you brought the sheaf of the wave offering, count off seven full weeks.