Leviticus 23:13-15

New Revised Standard Version Catholic Edition

¹³ And the grain offering with it shall be two-tenths of an ephah of choice flour mixed with oil, an offering by fire of pleasing odor to the Lord; and the drink offering with it shall be of wine, one-fourth of a hin. ¹⁴ You shall eat no bread or parched grain or fresh ears until that very day, until you have brought the offering of your God: it is a statute forever throughout your generations in all your settlements.

The Festival of Weeks

¹⁵ And from the day after the sabbath, from the day on which you bring the sheaf of the elevation offering, you shall count off seven weeks; they shall be complete.