Gregory the Dialogist

Ver.6. He hath made me, as it were, a byword of the people, and I am an example before them. This let blessed Job say in his own person, yea and in the voice of all of the Elect. For everyone that is stricken with the rod, is, as it were, 'made a byword of the people,' in that every fool, when he desires to curse anyone, takes up his cursing in a likeness to him, whom he sees stricken with a temporal stroke, and wishes that punishment for his adversary, which he sees to have befallen the righteous man. …

Morals on the Book of Job, Book XIII ↗

Thomas Aquinas

Just as Eliphaz promised temporal goods to those doing good, so also he asserted that all temporal adversities come about because of the sins of the one who suffers them. Since Job had suffered many adversities, Eliphaz uses him as an example to the people, and as he expresses this saying, "He has used me as a proverb to the people and his example in their midst." This is because to prove his opinion about the cause of adversities he used Job as an example, presuming he was punished for sin.

Commentary on Job ↗