The Mekhilta, compiled around the 2nd century CE as a halakhic commentary on Exodus, addresses a critical question about when the Passover laws took effect. The verse states plainly: "And it shall be, when you come to the land" (Exodus 12:25). The rabbis read this as a conditional — the obligation to observe these rites was contingent upon entering the Promised Land.
This raised an obvious problem. The Israelites celebrated a Passover in the wilderness, in their second year after leaving Egypt. If the commandment only activated upon entering the land, how do we explain the desert Passover?
The Mekhilta resolves this by noting that the wilderness Passover was a special, one-time Divine command — God explicitly instructed Moses to conduct it (Numbers 9:1-5). It was not evidence of an ongoing obligation during the desert years. Rather, it was an exception that proved the rule. The general statute of Passover observance would only become permanently binding once Israel crossed into the land "as He has spoken."
The phrase "as He has spoken" further confirms that God had already promised the land. The Passover ritual was thus woven into the covenant of settlement. It was not simply a memorial of liberation from Egypt. It was a forward-looking obligation, tied to arrival, inheritance, and the establishment of Israel in its homeland. The commandment waited for its people to arrive.