Judah had experienced firsthand how the Lord punishes; the ten tribes with the capital Samaria was destroyed forty years before these events—just before Manasseh started to reign. The prophets who spoke on behalf of the Lord brought that to the people’s attention by mentioning “the measuring line of Samaria.” The measuring line was a tool used to exactly measure horizontal building activities. Here, the measuring line is not used for exact building measurements, but for a thorough destruction—such as Samaria. The plumb line was used for vertical building activities. As thorough as the plumb line was used for the destruction of the reign of Ahab (see 1 Kings 16:29–33), it will now also be used in Jerusalem. Manasseh came after Ahab (see 2 Kings 21:3).
2 Kings 21:13 ends with the comparison of a dish. When it has leftover food in it, it will mold and rot. That contamination must be removed, so the dish must be cleansed (with or without water) and then put away upside down, to let it drain. This is how the Lord will treat Jerusalem, it will be cleansed of all the dirt by turning the city upside down.
13 And I will stretch over Jerusalem the measuring line of Samaria, and the plumb line of the house of Ahab, and I will wipe Jerusalem as one wipes a dish, wiping it and turning it upside down.