God prepares Jeremiah for a highly complex mission, granting him the resilience and protection needed to face fierce opposition. Tasked with delivering harsh rebukes, the prophet requires both a divine guarantee of safety and a sharp sense of discernment to truly understand his audience. The primary approach among commentators is that God transforms Jeremiah into a symbol of strength, much like a powerful fortress. He is made into an unyielding wall so that he will not fear the people when confronting them with their wrongdoings. Some add that this role specifically functions as a watchtower, giving him a clear vantage point over the nation [ביאור שטיינזלץ].
Beyond sheer defense, the prophet serves an active role as an examiner. This creates a dual reality where he is both an unconquerable, experienced stronghold and the very instrument through which the nation is tested [מלבי״ם]. A natural connection exists between his identity as a strong tester and the direct command he receives to investigate the people [רד״ק, אברבנאל]. He is instructed to search out, examine, and fully recognize their behavior. According to some commentators, the purpose of this continuous testing is to rebuke the nation repeatedly until the prophet reaches a final, undeniable conclusion: they simply refuse to listen [רש״י, מצודת דוד].
A deeper layer of this examination is understood through the metaphor of a silversmith purifying silver from dross. The nation is compared to raw metal heavily mixed with waste. Within this society, different groups of sinners constantly blame one another, with each faction entirely convinced that they are the pure silver while the others are the worthless scrap. In this scenario, the prophet takes on the role of the master refiner. The spirit of God within him, along with his sharp rebukes, act as the fire and the melting pot designed to purify the people. Ultimately, however, this careful process yields nothing. The profound examination reveals that the entire nation is composed of inseparable waste and wickedness that cannot be repaired, marking the complete failure of the refining process [מלבי״ם, אברבנאל].