Leviticus 23:14-16

Revised Standard Version Catholic Edition

¹⁴ And you shall eat neither bread nor grain parched or fresh until this same day, until you have brought the offering of your God: it is a statute for ever throughout your generations in all your dwellings.

The Festival of Weeks

¹⁵ “And you shall count from the morrow after the sabbath, from the day that you brought the sheaf of the wave offering; seven full weeks shall they be, ¹⁶ counting fifty days to the morrow after the seventh sabbath; then you shall present a cereal offering of new grain to the Lord.