That unclean donkey is yourself! (Charles Spurgeon)

"You must redeem the firstborn donkey with a lamb. But if you do not redeem it--you must kill the donkey by breaking its neck!" Exodus 34:20
Every firstborn creature must be the Lord's--but since the donkey was unclean, it could not be presented in sacrifice to Him. What then? Should it be allowed to go free from the universal law? By no means! God admits of no exceptions. The donkey is His due--but He will not accept it; He will not abate the claim--but yet He cannot be pleased with the unclean victim. No way of escape remained, but redemption--the donkey must be saved by the substitution of a lamb in its place; or if not redeemed, it must die!
My soul, here is a lesson for you! That unclean donkey is yourself! You are justly the property of the Lord who made you and preserves you--but you are so sinful that God will not, cannot, accept you! It has come to this--the Lamb of God must stand in your stead--or you must die eternally! Let all the world know of your gratitude to that spotless Lamb who has died for you, and so redeemed you from the fatal curse of the law!
Must it not sometimes have been a question with the Israelite, as to which should die--the donkey or the lamb? Would not the man pause to estimate and compare the values of these animals? Assuredly there was no comparison between the value of a sinful man--and the spotless Lord Jesus! Yet the Lamb dies--and man the donkey is spared! My soul, admire the boundless love of God to you! Vile worms are bought--with the blood of the holy Lamb of God! Dust and ashes are redeemed--with a price far above silver and gold! What a doom would have been mine--had not plenteous redemption been found!
The breaking of the neck of the donkey was but a momentary penalty. But who shall measure the eternal wrath to come--to which no limit can be imagined! Inestimably dear is the glorious Lamb--who has redeemed me from such a doom!