2 Chronicles 35:17
"And the children of Israel that were present kept the passover at that time, and the feast of unleavened bread seven days."
Cross References (ranked by relevance)
Deuteronomy 16:8
Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the LORD thy God: thou shalt do no work therein.
Exodus 23:15
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:)
Exodus 34:18
The feast of unleavened bread shalt thou keep. Seven days thou shalt eat unleavened bread, as I commanded thee, in the time of the month Abib: for in the month Abib thou camest out from Egypt.