C. F. Keil and Franz Delitzsch on 2 Kings 21:13

2Ki 21:13 “I stretch over Jerusalem the measure of Samaria, and the plummet of the house of Ahab.” The measure (קו) and the plummet (משׁקלת, lit., a level) were applied to what was being built (Zec 1:16), and also to what was being made level with the ground, i.e., completely thrown down (Amo 7:7). From this sprang the figurative expressions, measure of desolation and plummet of devastation (Isa 34:11). - The measure of Samaria therefore denotes the measure which was applied to the destruction of Samaria, and the plummet of the house of Ahab denotes the extermination of the royal house of Ahab. The meaning is: I shall destroy Jerusalem as I have destroyed Samaria, and exterminate its inhabitants like the house of Ahab. In the second hemistich the same thing is expressed, if possible, still more strongly: “I wipe away Jerusalem as one wipes the dish, and (having) wiped (it), turns it upon its upper side (פּניה).” The wiping of a dish that has been used, and the turning over of the dish wiped, so as not to leave a single drop in it, are a figurative representation of the complete destruction of Jerusalem and the utter extermination of its inhabitants.