The Epistle of Barnabas

Now what do you think this is a symbol of, that a command was given to Israel, that men of the greatest wickedness should offer a heifer, and then kill and burn it, and that boys should take the ashes, put them into vessels, and wrap a stick with purple wool along with hyssop, and then the boys should sprinkle the people, one by one, to purify them from their sins? Consider how He speaks to you plainly. The calf is Jesus: the sinful men offering it are those who led Him to the slaughter.

But now the men are no longer guilty, no longer considered sinners. The boys that sprinkle are those who have proclaimed to us the forgiveness of sins and purification of heart. To them He gave authority to preach the Gospel, being twelve in number, corresponding to the twelve tribes of Israel.

But why are there three boys that sprinkle? To correspond to Abraham, Isaac, and Jacob, because these men were honored by God. And why was the wool placed on the wood? Because by wood Jesus holds His kingdom, so that through the cross those who believe in Him shall live forever.

But why was hyssop joined with the wool? Because in His kingdom the days will be evil and polluted in which we shall be saved, and because the one who suffers in body is healed through the cleansing power of hyssop. This is clear to us, but obscure to them because they did not hear the voice of the Lord.