Exodus 34:18-20

"The feast of unleavened bread shalt thou keep. Seven days shalt thou eat unleavened bread, as I commanded thee, at the time appointed in the month of Abib; for in the month of Abib thou camest out from Egypt. All that openeth the womb is mine; and all thy cattle that is male, the firstlings of cow and sheep. And the firstling of an ass thou shalt redeem with a lamb: and if thou wilt not redeem it, then thou shalt break its neck. All the firstborn of thy sons thou shalt redeem. And none shall appear before me empty."

These verses are so emphatically a commandment for Israel to observe the Passover, that we must stand amazed that Rawlinson could not find it among the annual festivals enjoined, which are three in number: (1) the Passover; (2) the Pentecost; and (3) that of Tabernacles. That these verses indeed are a reference to the Passover is certain, because: (1) the mention of the month of Abib (Nisan); (2) the unleavened bread; (3) the sanctity of the firstborn; and (4) their coming out of Egypt, absolutely forbid that they could apply to anything else.