I'm going to assume that you're referring to the deposition of Giles Corey in The Crucible.
Though initially supportive of the witch-craze, Giles has turned completely against it. And to show just how opposed he is to the hysterical goings-on in Salem, he takes to the witness stand in open court to make a formal deposition against Thomas Putnam. In that deposition, he says that a respected citizen claimed he overheard Putnam instructing his daughter to accuse George Jacobs of witchcraft so that he, Putnam, would get his hands on the accused's property.
The accusation is wholly plausible. Putnam knows full well that anyone accused of witchcraft will automatically have to forfeit their property, and that as he is the only man in town rich enough to buy up such vacant lots he sees this whole witch-craze as a great opportunity to increase his already substantial land-holdings.
Unfortunately for Giles, Judge Danforth turns the tables on him, demanding to know the identity of the supposedly fine, upstanding citizen who allegedly overheard Putnam. Giles refuses, and so is held in contempt of court, which ultimately leads to his death by torture.