He said to him: I will give you a parable. To what is this alike? To a trustworthy man in a city, with whom all the people of his city would leave deposits without witnesses. One man came and left [his deposits] with him before witnesses. Once he forgot, and left a deposit with him without witnesses. [The trustworthy man’s] wife said to him, “Come, let us deny it.” He said to her, “Because this fool acted improperly, shall we lose our trustworthiness?”

So too afflictions: when they are sent upon a person, they are put under oath: You shall go [onto him] only on such-and-such a day, and leave only on such-and-such a day, at such-and-such an hour, through such-and-such a person and through such-and-such a remedy. When the time came for them to leave, this man went to the house of idolatry. The afflictions said, “By right we should not leave.” Then they said again, “Because this fool acts improperly, shall we break our oath?”

And this is what Rabbi Yochanan said: What is [the meaning of] what is written, “And sicknesses, bad and faithful” (Devarim 28:59)? Bad in their mission, and faithful to their oath.