(Exodus 12:6) "And it shall be to you for a keeping": Why does the taking of the Pesach (Passover) precede its slaughtering by four days? R. Matia b. Charash says: It is written (Ezekiel 16:8) "And I passed by you and I saw you, and behold, your time was the time for love": There had arrived the (time for the fulfillment of the) oath that the Holy One Blessed be He had sworn to our father Abraham to redeem his children. But they had no mitzvot (commandments)h to engage in, which would enable their redemption, viz. (Ibid. 7) "Your breasts were firm" (an allusion to Moses and Aaron), "and your hair had sprouted" (an allusion to the elders), but you were naked and bare" (of mitzvoth). And the Holy One Blessed be He gave them two mitzvoth—the blood of the Paschal lamb and the blood of circumcision to engage in for their redemption. Thus (Ibid. 6) "And I passed by you and I saw you steeped in your blood." And it is written (Zechariah 9:11) "You, too—By the blood of your covenant I have sent forth your bound ones from the waterless pit." Therefore, the Holy One Blessed be He commanded the taking of the Pesach four days before its slaughtering, for reward is given only for the act.