Joshua 22:27-28, 34

On the contrary, it is to be a witness between us and you and the generations that follow, that we will worship the LORD at his sanctuary with our burnt offerings, sacrifices and fellowship offerings. Then in the future your descendants will not be able to say to ours, ‘You have no share in the LORD.’ “And we said, ‘If they ever say this to us, or to our descendants, we will answer: Look at the replica of the LORD’s altar, which our ancestors built, not for burnt offerings and sacrifices, but as a witness between us and you.’

And the Reubenites and the Gadites gave the altar this name: A Witness Between Us—that the LORD is God.