Two verses in the Torah appear to contradict each other about how long the Israelites were connected to Egypt. One verse states: "And the habitation of the children of Israel in the land of Egypt was four hundred and thirty years" (Exodus 12:40). But another verse records God telling Abraham: "and they shall serve them and they shall afflict them four hundred years" (Genesis 15:13). So which was it — four hundred years or four hundred and thirty?
The Mekhilta resolves this apparent contradiction with a precise chronological calculation. The four hundred and thirty years did not begin when the Israelites entered Egypt. They began thirty years before the birth of Isaac — at the Covenant Between the Pieces, when God first told Abraham that his descendants would be strangers in a foreign land. From that prophetic moment to the actual exodus, four hundred and thirty years elapsed.
The four hundred years, meanwhile, are counted from Isaac's birth to the exodus. Both numbers are correct; they simply have different starting points.
This matters because it reveals how the rabbis understood divine promises. God's words to Abraham were not vague predictions. They were precise down to the year. The countdown began the moment the prophecy was spoken — not when the suffering started, but when the future was declared. In rabbinic thinking, a divine decree is already a reality the instant it leaves God's mouth. The four hundred and thirty years prove that God keeps exact accounts.