Plumb Line
This is what he showed me: The Lord was standing by a wall that had been built true to plumb, with a plumb line in his hand.
Amos 7:7-8
And the Lord asked me, “What do you see, Amos?”
“A plumb line,” I replied.
Then the Lord said, “Look, I am setting a plumb line among my people Israel; I will spare them no longer.