For though thou shalt wash thee with {g} lye, and take thee much soap, yet thy iniquity is marked before me, saith the Lord GOD.

(g) Though you use all the purifications and ceremonies of the law, you cannot escape punishment.

Wesley's Notes

2:22 Nitre - Though interpreters do greatly vary in describing what is particularly meant here by Nitre and Soap, and would be superfluous to mention here; yet all agree, they are some materials that artists make use of for cleansing away spots from the skin. The blot of this people is by no art to be taken out; nor expiated by sacrifices; it is beyond the power of all natural and artificial ways of cleansing. Marked - Thy filthiness is so foul that it leaves a brand behind which cannot be hid or washed out, but will abide, Jer 17:1.

Jamieson-Fausset-Brown Bible Commentary

22. nitre-not what is now so called, namely, saltpeter; but the natron of Egypt, a mineral alkali, an incrustation at the bottom of the lakes, after the summer heat has evaporated the water: used for washing (compare Job 9:30; Pr 25:20).

soap-potash, the carbonate of which is obtained impure from burning different plants, especially the kali of Egypt and Arabia. Mixed with oil it was used for washing.

marked-deeply ingrained, indelibly marked; the Hebrew, catham, being equivalent to cathab. Others translate, "is treasured up," from the Arabic. Maurer from a Syriac root, "is polluted."

Matthew Henry's Concise Commentary

2:20-28 Notwithstanding all their advantages, Israel had become like the wild vine that bears poisonous fruit. Men are often as much under the power of their unbridled desires and their sinful lusts, as the brute beasts. But the Lord here warns them not to weary themselves in pursuits which could only bring distress and misery. As we must not despair of the mercy of God, but believe that to be sufficient for the pardon of our sins, so neither must we despair of the grace of God, but believe that it is able to subdue our corruptions, though ever so strong.