For I will cleanse their blood [which] I have not cleansed,
&c.] Which some understand, as the Targum, of the Lord's, inflicting further punishments on the, enemies of his people, for shedding their innocent blood; and that he will not expiate their sins, nor hold them guiltless, or suffer them to go unpunished; but rather this is to be interpreted in a way of grace and mercy, as a benefit bestowed on Judah and Jerusalem, who are the immediate antecedents to the relative here; and in the words a reason is given why they should dwell safely and peaceably for ever, because the Lord will justify them from their sins; forgive their iniquities; cleanse them from all their pollution, signified by blood; of which grace they will have had no application made to them till this time; but now all their guilt and faith will be removed; and particularly God will forgive, and declare to be forgiven their sin of crucifying Christ; whose blood they had imprecated upon themselves and their children, and which has remained on them; but now will be removed, with all the sad effects of it. Though this may also refer to the conversion of the Gentiles, and the pardon of their sins, and the sanctification of their persons, in such places and parts of the world, where such blessings of grace have not been bestowed in times past for many ages, if ever; for the Lord dwelleth in Zion;
and therefore will diffuse his grace, and spread the blessings of it all around: or "even the Lord [that] dwelleth in Zion" F4; he will do what is before promised; being the Lord, he can do it; and dwelling in Zion his church, it may be believed he will do it; and this will be for ever, when his Shechinah shall return thither in the days of the Messiah, as Kimchi observes.
F4 (hwhyw) "even I the Lord", margin of our Bibles.