Epistle of Barnabas

Now what do you suppose this to be a type of, that a command was given to Israel, that men of the greatest wickedness should offer a heifer, and slay and burn it, and, that then boys should take the ashes, and put these into vessels, and bind round a stick purple wool along with hyssop, and that thus the boys should sprinkle the people, one by one, in order that they might be purified from their sins? Consider how He speaks to you with simplicity. 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, are no longer regarded as sinners. And the boys that sprinkle are those that have proclaimed to us the remission of sins and purification of heart. To these 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, and Isaac, and Jacob, because these were great with God. And why was the wool [placed] upon the wood? Because by wood Jesus holds His kingdom, so that [through the cross] those believing on Him shall live for ever.

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 he who suffers in body is cured through the cleansing efficacy of hyssop. And on this account the things which stand thus are clear to us, but obscure to them because they did not hear the voice of the Lord.