Jeremiah 2:22
For though thou wash thee with nitre, and take thee much soap, yet thine iniquity is marked before me, saith the Lord GOD. For though thou wash thee with nitre, and take thee much soap, yet thine iniquity is marked before me, saith the Lord GOD.
No amount of washing with nitre and taking much soap can remove guilt by outward cleansing, for iniquity remains marked and known before God and sin cannot be concealed from Him. In its setting this belongs to God's charge that His people had abandoned Him and turned away from Him. That charge is that they exchanged their glory for what does not profit.
Their turning from God is described as becoming corrupt. Applied to the publishing institution, this warns that its wrongs and corruption are not erased by outward appearances or claims of purity. It applies to people who lay aside God's Word for human teachings.