Why God Redeemed Israel the Lamb with Egypt the Donkey

Another interpretation of (Numbers 3:40) "Number every firstborn male." The Holy One, blessed be He, said: For the sake of My love for Israel I altered the order of the world. How so? I wrote in My Torah that a donkey should be redeemed with a lamb, as it is said (Exodus 34:20), "And the firstling of a donkey you shall redeem with a lamb." Yet I did not do so; rather, I redeemed a lamb with a donkey. The Egyptians are likened to a donkey, as it is said (Ezekiel 23:20), "whose flesh is the flesh of donkeys"; and Israel are called a lamb, as it is said (Jeremiah 50:17), "Israel is a scattered sheep." And I slew the firstborn of the Egyptians, and I sanctified the firstborn of Israel, as it is said (Numbers 8:17), "For every firstborn among the children of Israel is Mine, of man and of beast; on the day that I struck down every firstborn in the land of Egypt I sanctified them for Myself." Therefore He said to him, "Number every firstborn male among the children of Israel."