Jeremiah is acting as God’s agent here in the metaphor of refining silver. God asks him to “test” his fellow countrymen…discerning their hollow words of devotion and examining their false integrity. In the verses that follow, (28-30) we see how the refining process has yielded nothing of value…the people stubbornly remaining unfaithful, wicked, and completely hardened to Jeremiah’s warnings…their worship deemed as worthless.