Exodus 23:15

You are to keep the Feast of Unleavened Bread as I commanded you: At the appointed time in the month of Abib you are to eat unleavened bread for seven days, because that was the month you came out of Egypt. No one may appear before Me empty-handed.

Note That is, the seven-day period after the Passover during which no leaven may be eaten; see Exodus 12:14–20.

Note Abib was the first month of the ancient Hebrew lunar calendar, usually occurring within the months of March and April.

Thou shalt keep the feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty:)

You shall observe the feast of unleavened bread. Seven days you shall eat unleavened bread, as I commanded you, at the time appointed in the month Abib (for in it you came out of Egypt), and no one shall appear before me empty.

The feast of unleavened bread shalt thou keep: seven days thou shalt eat unleavened bread, as I commanded thee, at the time appointed in the month Abib (for in it thou camest out from Egypt); and none shall appear before me empty: