Charles Spurgeon Commentary Exodus 12:6-10

"and ye shall keep it until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it at even. And they shall take of the blood, and put it on the two side-posts and on the lintel, upon the houses wherein they shall eat it. And they shall eat the flesh in that night, roast with fire, and unleavened bread; with bitter herbs they shall eat it. Eat not of it raw, nor boiled at all with water, but roast with fire; its head with its legs and with the inwards thereof. And ye shall let nothing of it remain until the morning; but that which remaineth of it until the morning ye shall burn with fire." — Exodus 12:6-10 (ASV)

And you shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening. And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it. And they shall eat the flesh in that night, roast with fire, and unleavened bread; and with bitter herbs they shall eat it. Eat not of it raw, nor sodden at all with water, but roast with fire; his head with his legs, and with the purtenance thereof.

And you shall let nothing of it remain until the morning; and that which remains of it until the morning you shall burn with fire.

Everything was to be done exactly according to God's order; the alteration of the slightest detail would have spoiled it all. I wish that all Christians would remember this rule with regard to the ordinances of God's house. They are not for us to make, or for us to alter, but for us to keep.