25. The external restoration must be preceded by an internal one. The change in their condition must not be superficial, but must be based on a radical renewal of the heart. Then the heathen, understanding from the regenerated lives of God's people how holy God is, would perceive Israel's past troubles to have been only the necessary vindications of His righteousness. Thus God's name would be "sanctified" before the heathen, and God's people be prepared for outward blessings.
      sprinkle . . . water--phraseology taken from the law; namely, the water mixed with the ashes of a heifer sprinkled with a hyssop on the unclean (Nu 19:9-18); the thing signified being the cleansing blood of Christ sprinkled on the conscience and heart (Heb 9:13, 14; 10:22; compare Jer 33:8; Eph 5:26).
      from all your idols--Literal idolatry has ceased among the Jews ever since the captivity; so far, the prophecy has been already fulfilled; but "cleansing from all their idols," for example, covetousness, prejudices against Jesus of Nazareth, is yet future.

JFB.