הלכה אויף דברים 24:22

In every generation, one must show himself as if he personally had come out from the subjugation of Egypt; as it is stated (Deuteronomy 6:23), "And He took us out from there, etc." And regarding this, the Holy One, blessed be He, commanded in the Torah (Deut. 5:15, 15:15, 24:22), "Remember that you were a slave" - meaning to say, as if you yourself had been a slave, came out to freedom, and were redeemed.