Josh 22:21

“But let us see what sacrament lies within this deed. The former people of the circumcision are represented in Reuben, who was the firstborn; but also in Gad, who also is the firstborn out of Zilpah; and Manasseh, no less a firstborn. But insofar as I say "firstborn," I speak chronologically. Therefore, these things are said not that it might be evident some division and separation is between us and those who were righteous before the coming of Christ, but that they might reveal themselves to still be our brothers even if they existed before the coming of Christ. For although they possessed an altar then before the coming of the Savior, nevertheless, they knew and perceived that it was not that true altar but that it was a form and figure of what would be the true altar. Those persons knew this because the true victims and those who were able to take away sins were not offered on that altar that the firstborn people possessed but on this one where Jesus was. Here the heavenly victims, here the true sacrifices are consumed. Therefore, they are made "one flock and one shepherd," those former righteous ones and those who are now Christians.”