But as for them whose heart walketh - Them whose affections are attached to idolatry, they shall have such reward as their idols can give them, and such a recompense as Divine justice shall award them.
Compare Ezekiel 11:19
One heart - So long as the Israelites were distracted by the service of many gods, such unity was impossible; but now, when they shall have taken away the “abominations” from the land, they shall be united in heart to serve the true God.
Stony heart heart of flesh - The heart unnaturally hardened, and the heart reawakened to feelings proper to man.