The general meaning is plain, but the exact force of the metaphor used is not so clear. If the "line" and the "plummet" be "symbols of rule" or law, the meaning will be - "I will apply exactly the same measure and rule to Jerusalem as to Samaria - I will treat both alike with strict and even justice."

The line of Samaria - I will treat Jerusalem as I have treated Samaria. Samaria was taken, pillaged, ruined, and its inhabitants led into captivity; Jerusalem shall have the same measure.

And the plummet of the house of Ahab - The house of Ahab was totally destroyed, and not a man of his race left to sit upon the throne of Israel: so shall it be done to the house or royal family of Judah; they shall be all finally destroyed, and not a man of their race shall any more sit on the throne of Judah; nor shall Judah have a throne to sit on. Thus Jerusalem shall have the same weight as well as the same measure as Samaria, because it has copied all the abominations which brought that kingdom to total destruction.

I will wipe Jerusalem as a man wipeth a dish - The Vulgate translates this clause as follows: Delebo Jerusalem, sicut deleri solent tabulae; "I will blot out Jerusalem as tablets are wont to be blotted out." This is a metaphor taken from the ancient method of writing: they traced their letters with a stile on boards thinly spread over with wax; for this purpose one end of the stile was sharp, the other end blunt and smooth, with which they could rub out what they had written, and so smooth the place and spread back the wax, as to render it capable of receiving any other word. Thus the Lord had written down Jerusalem, never intending that its name or its memorial should be blotted out. It was written down The Holy City, The City of the Great King; but now God turns the stile and blots this out; and the Holy Jerusalem, the City of the Great King, is no longer to be found! This double use of the stile is pointed out in this ancient enigma: -

De summo planus; sed non ego planus in imo:

Versor utrinque manu, diverso et munere fungor:

Altera pars revocat, quicquid pars altera fecit.

"I am flat at the top, but sharp at the bottom;

I turn either end, and perform a double function:

One end destroys what the other end has made."

But the idea of emptying out and wiping a dish expresses the same meaning equally well. Jerusalem shall be emptied of all its wealth, and of all its inhabitants, as truly as a dish turned up is emptied of all its contents; and it shall be turned upside down, never to be filled again. This is true from that time to the present hour. Jerusalem is the dish turned upside down, the tablet blotted out to the present day! How great are God's mercies! and how terrible his judgments!

And I will stretch over Jerusalem the line of Samaria,.... The Targum is, the line of destruction; and the sense is, that the same measure should be measured to Jerusalem as was to Samaria; that is, the same lot and portion should befall one as the other, that is, be utterly destroyed:

and the plummet of the house of Ahab; the Targum is, the weight or plummet of tribulation; signifying, that the same calamities should come upon the families of Jerusalem, and especially on the family of Manasseh as came upon the family of Ahab. It is a metaphor from builders that take down as well as raise up buildings by rule and measure, see 2 Samuel 8:2.

and I will wipe Jerusalem, as a man wipeth a dish, wiping it, and turning it upside down; as when one takes a dish or cup that has broth in it, or any liquid, as oil; and the Septuagint render it alabaster, in which ointment used to be put; and wipes it clean, that nothing may appear in it; and then turns it with its mouth downward, that, if any thing should remain, it might drain out; signifying hereby the emptying o Jerusalem of its palaces and houses, wealth and riches and of all its inhabitants; and yet the empty dish being preserved, seems to denote the restoration of Jerusalem after the seventy years' captivity. According to the Vulgate Latin version, the metaphor is taken from the blotting out of writing tables, and turning and rubbing the style upon them till the writing is no more seen.

"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 (Zechariah 1:16), and also to what was being made level with the ground, i.e., completely thrown down (Amos 7:7). From this sprang the figurative expressions, measure of desolation and plummet of devastation (Isaiah 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.

And I will stretch over Jerusalem the line {d} of Samaria, and the plummet of the house of Ahab: and I will wipe Jerusalem as a man wipeth a dish, wiping it, and turning it upside down.

(d) As I have destroyed Samaria and the house of Ahab so will I destroy Judah.

21:13 The line - She shall have the same measure, the same judgments which Samaria had. The line is often put for one's lot or portion, because mens portions or possessions used to be measured by lines. A dish - As men do with a dish that hath been used, first wholly empty it of all that is in it, then throughly cleanse and wipe it; and lastly, turn it upside down, that nothing may remain in it; so will I deal with Jerusalem, throughly empty and purge it from all its wicked inhabitants. Yet the comparison intimates, that this should be in order to the purifying, not the final destruction of Jerusalem. The dish shall not be broken in pieces, or wholly cast away, but only wiped.

wiping...: Heb. he wipeth and turneth it upon the face thereof

13. the line of Samaria, and the plummet of the house of Ahab-Captives doomed to destruction were sometimes grouped together and marked off by means of a measuring-line and plummet (2Sa 8:2; Isa 34:11; Am 7:7); so that the line of Samaria means the line drawn for the destruction of Samaria; the plummet of the house of Ahab, for exterminating his apostate family; and the import of the threatening declaration here is that Judah would be utterly destroyed, as Samaria and the dynasty of Ahab had been.

I will wipe Jerusalem, &c.-The same doom is denounced more strongly in a figure unmistakably significant.

21:10-18 Here is the doom of Judah and Jerusalem. The words used represent the city emptied and utterly desolate, yet not destroyed thereby, but cleansed, and to be kept for the future dwelling of the Jews: forsaken, yet not finally, and only as to outward privileges, for individual believers were preserved in that visitation. The Lord will cast off any professing people who dishonour him by their crimes, but never will desert his cause on earth. In the book of Chronicles we read of Manasseh's repentance, and acceptance with God; thus we may learn not to despair of the recovery of the greatest sinners. But let none dare to persist in sin, presuming that they may repent and reform when they please. There are a few instances of the conversion of notorious sinners, that none may despair; and but few, that none may presume.