רַבָּן גַּמְלִיאֵל Rabban Gamliel would say: Anyone who does not say these three things on Pesaḥ has not fulfilled his obligation, and these are they: PESAḤ, MATZA, AND BITTER HERBS.

The PESAḤ is what our ancestors would eat while the Temple stood: and what does it recall? It recalls the Holy One’s passing over (Pasah) the houses of our ancestors in Egypt, as it is said: “You shall say: ‘It is a Pesaḥ offering for the LORD, for He passed over the houses of the children of Israel in Egypt while He struck the Egyptians, but saved those in our homes’ – and the people bowed and prostrated themselves.”

The matzot are now lifted:

THIS MATZA that we eat: what does it recall? It recalls the dough of our ancestors, which did not have time to rise before the King, King of kings, the Holy One, blessed be He, revealed Himself and redeemed them, as it is said: “They baked the dough that they had brought out of Egypt into unleavened cakes, for it had not risen, for they were cast out of Egypt and could not delay, and they made no provision for the way.”

The bitter herbs are now lifted:

THESE BITTER HERBS that we eat: what do they recall? They recall the bitterness that the Egyptians imposed on the lives of our ancestors in Egypt, as it is said: “They embittered their lives with hard labor, with clay and with bricks and with all field labors, with all the work with which they enslaved them – hard labor.”

בְּכָָל דּוֹר וָדוֹר GENERATION BY GENERATION, each person must see himself as if he himself had come out of Egypt, as it is said: “And you shall tell your child on that day, ‘Because of this the LORD acted for me when I came out of Egypt.’” It was not only our ancestors whom the Holy One redeemed; He redeemed us too along with them, as it is said: “He took us out of there, to bring us to the land He promised our ancestors and to give it to us.”