Othello Act 4, Scene 2: "The Citadel."
Emilia tells Othello that Desdemona has never been alone with Cassio, nor has she whispered, or given any indication of an affair. Othello sends Emilia to summon Desdemona and dismisses everything that she says on the basis that she is a simple woman. Iago has already convinced him that Desdemona is unchaste. Othello curses and damns Desdemona, calling her a whore and ignoring everything she says. He persistently insults Emilia, finally dismissing her from the conversation and stage. A worried Emilia questions Desdemona about the conversation, but Desdemona simply replies that she no longer has a husband, and feels faint.
Iago enters on Emilia's despair. She is enraged and feels deeply concerned for her lady, Desdemona. She claims that whoever the man is who planted such ideas of whoredom into Othello's mind, is a "most villainous knave, / Some base notorious knave, some scurvy fellow" Act 4, Scene 2. Desdemona begs honest Iago for help, for Othello trusts Iago more than any other. After the women leave, Roderigo enters, complaining to Iago. He believes that he has received no benefits from this plan. Iago lays out his plan for the eveningahead to Roderigo: Bianca and Cassio's dinner; and Othello's plans to remove Cassio from Cyprus. Roderigo is to enter the dinner and remove Cassio himself.