(Exodus 13:5) speaks of the land "which He swore to your forefathers." The Mekhilta asks a direct question: where exactly in the Torah did God swear this oath to each of the patriarchs?
The answer traces three distinct moments. To Abraham, the oath appears in (Genesis 15:18): "On that day the Lord made a covenant with Abraham, saying, 'To your seed I have given this land.'" This was the Covenant Between the Parts, the foundational promise that linked Abraham's descendants to a specific territory.
To Isaac, the oath appears in (Genesis 26:3): "Live in this land, and I will be with you and bless you." God repeated the promise directly to Isaac, confirming that the covenant was not a one-time event but a renewable inheritance passed from father to son.
To Jacob, the oath appears in (Genesis 28:13): "The land on which you are lying — to you I will give it and to your seed." This was the vision at Bethel, where Jacob slept on a stone and saw angels ascending and descending a ladder reaching heaven.
The Mekhilta then adds a teaching from Rabbi Nathan: "Then you shall perform this service" — the same Passover service observed in Egypt must continue in all future generations. The oath to the patriarchs was not just about land. It was about perpetual practice. The service that began in slavery would continue in freedom, binding every generation to the night they were redeemed.