Joel 3:21

For I will cleanse their blood [that] I have not cleansed: for the LORD dwelleth in Zion.

Ver. 21. For I will cleanse their blood that I have not cleansed] i.e. I will clear their consciences from dead works, from the stain and sting of all sin, that they may not question their right to these precious promises, but boldly take the comfort of them. I will say unto them, Such were some of you, but ye are washed, but ye are justified, but ye are sanctified. Be of good cheer, therefore, since your sins, your bloody sins, are forgiven you. Or thus, "I will cleanse their blood," that is, I will declare that the blood of the godly, which the world thought to have been justly spilt, was indeed innocent blood, and that they were slain without cause. This I will do, partly by rooting out and damning their enemies, and partly by clearing their innocence, and crowning their constancy. Thus Mercer, Levely, &c.

For the Lord dwelleth in Zion] This is the last promise, but not the least. It referreth, saith Danaeus, to Christ taking our flesh, by the which he dwelt among us, being God manifest in the flesh, 1Ti 3:16 John 1:14, "The Word was made flesh, and dwelt among us, and we saw the glory thereof," &c. This is reserved to the last place, as the causa et cumulus felicitatis, especially since he dwelleth with his Church for ever, as it is in the precedent verse, and maketh her a true Jehovah Shammah, as she is called Ezekiel 48:35 .