Plumb Line - Amos 7:7-8

7 Thus he shewed me: and, behold, the Lord stood upon a wall made by a plumbline, with a plumline in his hand.

8 And the Lord said unto me, Amos, what seest thou? And I said, A plumbline. Then said the Lord, Behold, I will set a plum line in the midst of my people Israel: I will not again pass by them more:

measures the people's righteousness