From this verse we again learn, that Zechariah promised the spirit of repentance to the Jews, so that they would find God still propitious to them, when their circumstances were brought to the verge of despair: for it would not have been enough for them to feel sorrow, except God himself became propitious and merciful to them. He had said indeed that the Spirit of grace and of commiserations would be poured forth; but he had not as yet taught clearly what he now adds respecting remission and pardon. After having then declared that there would be felt by the Jews the bitterest sorrow, because they had as it were pierced God, he now mentions the fruit of this repentance. And hence also appears what Paul means by sorrow not to be repented of; for it generates repentance unto salvation. When then our sorrow is blessed by the Lord, the end is to be regarded; for our hearts are thereby raised up to joy. But the issue of repentance, as Zechariah declares here, is ablution: and he alludes to the legal rites when he says,

A fountain shall be opened to the house of David, and to the inhabitants of Jerusalem. We know that formerly under the law many washings were prescribed to the Jews; and when any one had become defiled, to wash himself was the remedy. It is certain that water was of no value to cleanse the heart; but the sins of men, we know, are expiated by the death of Christ, so that true ablution is by the blood which he shed for us. ¹⁶⁷¹⁶⁷     Jerome and Cyril say that the “fountain” is baptism; but Theodoret with more wisdom considered it to be the blood of Christ. Marckius regarded it as the grace of God flowing to us through the merits of the Redeemer, and applied for justification and sanctification. The word “fountain,” says Drusius, intimates the perennity and abundance of grace. — Ed. Hence the types of the law ought no doubt to be referred to this blood. The meaning is that God would be reconciled to the Jews when they became touched with sincere sorrow, and that reconciliation would be ready for them, for the Lord would cleanse them from every defilement.

He speaks of a fountain opened; and he no doubt intimates here a difference between the law and the gospel. Water was brought daily to the temple; but it was, we know, for private washings. But Zechariah promises here a perpetual stream of cleansing water; as though he had said, “Ablution will be free to all, when God shall again receive his people into favor.” Though remission of sins was formerly offered under the law, yet it is now much more easily obtained by us; not that God grants a license to sin, but that the way in which our filth is cleansed, has become more evident since the coming of Christ. For the fathers under the law were indeed fully assured that God was so propitious as not to impute sins; but where was the pledge of ablution? In the sprinkling of blood, and that blood was the blood of a calf or a lamb. Now since we know that we have been redeemed by Christ, and that our souls are sprinkled with his blood by the hidden power of the Holy Spirit, it is doubtless the same as though God had not only set before our eyes our ablution, but also placed it as it were in our hands, while to the fathers it was more obscure or shown to them at a distance.

And he says, To the house of David and to the inhabitants of Jerusalem. He had before restricted God’s favor to that city, that he might goad the Jews, who had preferred their outward gratifications to so great a happiness; for they thought themselves happy in their exile, because they inhabited a pleasant and fruitful country, and enjoyed quietness and peace; and thus it happened that they despised the deliverance offered to them. Hence the Prophet promises here to the citizens of Jerusalem and to the royal family a fountain in which they might wash away their filth; for from Sion was the law to go forth, and from Jerusalem the word of the Lord. (Isaiah 2:2.) And we know that from thence were taken the first-fruits of the new Church. ¹⁶⁸¹⁶⁸     The house of David and the inhabitants of Jerusalem were specifically mentioned, says Grotius, because they had grievously offended. The design seems to have been to point out those who had been most guilty, who had been themselves the murderers of their own Messiah. This fountain was yet opened for them. — Ed. What we have before seen respecting God’s favor being extended farther, is no objection; for both events were in their due order fulfilled, as God blessed the tribe of Judah, who trusted in his promises and returned to their own country, and afterwards extended wider his favor, and gathered into one body those who had been dispersed through distant parts of the world.

He adds, For sin and for uncleanness, or as some read, “for sprinkling,” which is by no means suitable, except the word “sin” be taken for expiation. The word is derived from נדד, nedad, but it often means sprinkling, sometimes uncleanness, and sometimes the uncleanness of women, and so some render it here. The verb signifies to remove or to separate; and hence נדה, nede, is the removal of a woman from her husband during her uncleanness, but it is applied to designate any uncleanness. It might indeed be taken here for the uncleanness of women, as an instance of a part for the whole; but I am led by the context to render it uncleanness. Now if we translate חטאת, chathat, sin, then נדה, nede, must be rendered uncleanness; but if the first be expiation, then the second may be sprinkling: and this meaning I am disposed to take, for under the law sins were cleansed by sacrifices as well as by washings. ¹⁶⁹¹⁶⁹     
   For sin and defilement, Newcome
   For guilt and for uncleanness, Henderson
   Our version cannot be mended “for sin and for uncleanness.” The latter word, [נדה], has been strangely rendered by some. Its first meaning is removal or separation, which took place in case of uncleanness: but it is also used to designate the cause of removal, even uncleanness, and that generally, as we find from Ezra 9:11, where the “land” is said to be “unclean ([נדה]) with the filthiness ([נדת]) of the people,” or rather polluted with the pollution of the people “of the lands.” It is used in this text as synonymous with [טמא], which means what is unclean, defiled, or polluted. See Ezra 6:21
   This verse is most strangely rendered by the Septuagint, in a way quite unaccountable. The three other versions — Aq., Sym., and Theod., — are not very far from the original. — Ed.

The import of the whole then is — that though the Jews had in various ways defiled themselves, so that they were become filthy before God, and their uncleanness was abominable, yet a fountain would be prepared for them, by which they might cleanse themselves, so as to come before God pure and clean. We hence see that it was the Prophet’s object to show, that the repentance of which he had spoken would not be useless, for there would be a sure issue, when God favored the Jews, and showed himself propitious to them, and already pacified, and even provided for them a cleansing by the blood of his only-begotten Son, so that no filth might prevent them to call on him boldly and in confidence; for instead of the legal rites there would be the reality, as their hearts would be sprinkled by the Spirit, so that they would be purified by faith, and would thus cast away all their filth.