Exodus 23:15-16

You are to keep the feast of unleavened bread; for seven days let your bread be without leaven, as I gave you orders, at the regular time in the month Abib (for in it you came out of Egypt); and let no one come before me without an offering: And the feast of the grain-cutting, the first-fruits of your planted fields: and the feast at the start of the year, when you have got in all the fruit from your fields.