Cassio meets with Desdemona about reinstating his lieutenancy. She agrees and promises to reinstates him.
"Assume thee, if I do vow a friendship, I'll preform it to the last article"
After Desdemona pleads for Cassio's case, she leaves and Iago and Othello are left alone. Iago tells Othello that he thinks that Desdemona is cheating on him with Cassio but that he shouldn't be jealous.
"O, beware, my lord, of jealously it is a green-eyed monster which doth mock the the meat it feeds on"
After being infuriated by Iago's claims, Othello threatens to kill Iago if he doesn't come up with any concrete evidence of Desdemona's infidelity.
"Give me the ocular proof, or, by the worth of mine eternal soul, thou hadst been better born a dog"
After Desdemona looses her handkerchief, Iago lies to Othello by saying that he saw Cassio rubbing his beard with it.
"Did I today see Cassio wipe his beard with"
After hearing this news, Othello plans to kill Desdemona and Iago plans to kill Cassio, after this Iago is promoted.
"Arise, black vengeance, from hollow hell!
Sfter finding the lost handkercheif in his room, Cassio asks his wife Bianca ro copy it for him
"I would have it copied. Take it and leave me for this time"