Joshua 22:10, 34

But while they were still in Canaan, and when they came to a place called Geliloth near the Jordan River, the men of Reuben, Gad, and the half-tribe of Manasseh stopped to build a large and imposing altar.

The people of Reuben and Gad named the altar “Witness,” for they said, “It is a witness between us and them that the LORD is our God, too.”