Barnabas, Epistle of Barnabas 8

What do you suppose the pattern means? God commanded Israel to offer a heifer, but the men who do so are people in whom sin has reached its full measure. After they slaughter and burn it, they take the ashes and throw them into a vessel, then put the red wool on wood — here again is the pattern of the cross, the red wool, and the hyssop — and so they sprinkle the children, one by one, the whole people, so that they may be purified from their sins (Numbers 19:1-10). Understand how simply He speaks to you. The heifer is Jesus. The men who offer it are the sinners who handed Him over for slaughter. After that there are no longer men; the glory of sinners is gone. The children who do the sprinkling are the ones who evangelized us with the forgiveness of sins and the purification of the heart, to whom He gave the authority of the gospel. There are twelve of them, for a testimony to the tribes — because there are twelve tribes of Israel — so that they might preach. Why are there three children who sprinkle? As a testimony to Abraham, Isaac, and Jacob, because these men are great before God. And why is the wool placed on the wood? Because the kingdom of Jesus is on the wood, and because those who hope in Him will live forever. Why both the wool and the hyssop? Because in His kingdom there will be evil and filthy days, in which we will be saved: for even the one who suffers in the flesh is healed through the filth of the hyssop. And because of this, what has happened this way is clear to us, but dark to them, because they did not hear the voice of the Lord.