With regard to God’s promise in Ezekiel 36:25 to purify the Israelites of idolatry by sprinkling them with water as they are brought out of captivity, Reformation exegetes debate whether the water refers to the waters of baptism, the blood of Christ, or both. In his commentary, Puritan William Greenhill (1591-1671) gives his argument for understanding the water as the blood of Christ, reading the text through the lens of Hebrews 12:24.
I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your impurities and from all your idols.
Commentary on Ezekiel 36:25
“Then will I sprinkle clean water on you.” When they were called and came out of Babylon, then the Lord would sprinkle clean water on them. The Jews by “water” mean the abundance of outward things. Some others interpret it as the water in baptism. But neither does the abundance of outward things or the water of baptism cleanse from the pollution of idols. . . . Some other sense of the word therefore must we seek out. By “water” the blood of Christ is intended, say the best expositors. Some make grace the thing; but that is too general, unless we limit it to the blood of Christ, which of grace is given to wash sinners with. These words, “I will sprinkle clean water on you,” have some allusion to the waters mingled with the ashes of the red cow, which being sprinkled by a branch of hyssop on the unclean party, he was cleansed. . . . This red cow figured Christ in his afflictions and sufferings; and the water mingled with the ashes of it, the blood of Christ, which is called “the blood of sprinkling” (Heb 12:24). The water they used in sprinkling was clean water, running or spring water, free from all filth. So the blood of Christ is pure; he was without sin and blemish, or spot. His blood was precious and pure (1 Pet 1:19), and here it is called “clean water.” This sprinkling of clean water on them is the application of the blood of Christ by the Spirit of God. As the priest was to take the blood of the red heifer with his finger and to sprinkle it, so God by the hand and finger of his Spirit does take and sprinkle the blood of Christ, that is, apply the fruit and benefit of it to the hearts of people.
Ezekiel, Daniel, ed. Carl L. Beckwith, Reformation Commentary on Sctipture, OT vol. 12, pp. 177-78.