Facing the misguided words of his friends, Job firmly rejects their attempts at comfort and rebuke. He realizes that their arguments rest on a fragile foundation and offer him no genuine help. Instead of providing support, his companions gather and attach false claims together, attempting to accuse him of a sin he never committed. Some view this behavior as a form of plastering or smearing, much like a person coating an oven, as the friends try to cover up the true reality with falsehoods [מלבי״ם, ביאור שטיינזלץ]. Because they build their entire case on the mistaken assumption that Job must have sinned, they are essentially constructing a tower on a completely broken foundation [אלשיך].
Consequently, Job views them as useless healers. Their advice urges him to repent to God in order to be cured of his agonizing pain. However, this guidance is absolute nonsense to him, as he carries no hidden guilt that requires repentance [מצודת דוד].
The exact nature of this useless healing is understood in a few different ways. The primary approach among commentators is that their remedies amount to nothing at all, lacking any real substance or value [רש״י, מצודת ציון, רלב״ג, ביאור שטיינזלץ]. They are simply doctors of nothingness. A more visual interpretation suggests that Job compares his friends to doctors trying to heal a broken idol or statue. Just as it is pointless to apply ointments and bandages to a mute, lifeless figure, the friends' educated arguments are entirely useless because they are built on a lie [רמב״ן, אלשיך]. Finally, an ancient tradition explains that this concept refers to a specific nerve in the neck for which there is no known medical cure. This vivid medical reality perfectly captures the absolute futility of the friends' words [רש״י, חומת אנך].