Othello Act II Scene 3

This crucial scene, after Cassio loses his position due to Iago's plotting against him, he turns to Iago for advice, and Iago advises him to speak to "the general's general" -- Desdemona --  to get her to plea for his cause with Othello.  In the meantime, Iago soothes Roderigo once again.  His plotting is clear.  But pay close attention to how he talks to Cassio about the importance of reputation.

See the text here.

See three different versions of the scene acted out here.