During the first month, on the fourteenth day of the month in the evening, is Adonai’s Passover.
On the fifteenth day of the same month is the Feast of Matzot to Adonai. For seven days you are to eat matzah. On the first day you are to have a holy convocation and you should do no regular work. Instead you are to present an offering made by fire to Adonai for seven days. On the seventh day is a holy convocation, when you are to do no regular work.
Adonai spoke to Moses saying: Speak to Bnei-Yisrael and tell them: When you have come into the land which I give to you, and reap its harvest, then you are to bring the omer of the firstfruits of your harvest to the kohen. He is to wave the omer before Adonai, to be accepted for you. On the morrow after the Shabbat, the kohen is to wave it. On the day when you wave the omer you are to offer a male lamb without blemish, one year old, as a burnt offering to Adonai. The grain offering with it should be two tenths of an ephah of fine flour mixed with oil—an offering made by fire to Adonai for a soothing aroma. Its drink offering with it should be a quarter of a gallon of wine. You are not to eat bread, roasted grain, or fresh grain until this same day—until you have brought the offering of your God. It is a statute forever throughout your generations in all your dwellings.
Then you are to count from the morrow after the Shabbat, from the day that you brought the omer of the wave offering, seven complete Shabbatot. Until the morrow after the seventh Shabbat you are to count fifty days, and then present a new grain offering to Adonai.
(Leviticus 23:5-16 TLV)