Soap
Archimandrite Nikifor’s Biblical Encyclopedia
(Jer. 2:22). If the Hebrews were not in fact acquainted with the preparation of what we properly call soap, that is, a mixture of a mineral alkaline salt with various oily substances, they were nevertheless fully acquainted with its property of cleansing and washing away various stains and impurities from the body and clothing. “For though thou wash thee with nitre, and take thee much soap,” it is said in the Book of the prophet Jeremiah, “yet thine iniquity is marked before me, saith the Lord GOD” (2:22)—that is, the sinful inclination of the Israelites toward idols had taken such deep root in their very being that nothing could wash this stain from them.