Jeremiah 2:22
For though you wash you with nitre, and take you much soap, yet your iniquity is marked before me, said the Lord GOD.
Nave's Topical Index—AKJV

Malachi 3:2
But who may abide the day of his coming? and who shall stand when he appears? for he is like a refiner's fire, and like fullers' soap:
Nave's Topical Index—AKJV