Look, the proof is right there in front of your eyes. You cant deny it.
Act 3, Scene 3 (3)
I will do as you command.
Screw you two!!! Iago, kill Cassio within the next three days!
Act 3, Scene 4
Just copy the embroidery for me please. I really like the design.
Othello questions Iago of what Iago thinks of Cassio and Desdemona. Iago withholds information in order to Othello to drag the information out of him. After much nagging by Othello, Iago tells him that Cassio is secretly in love in Desdemona and Desdemona is cheating on him for Cassio.
Othello tells Desdemona about the handkerchief and then asks for it to test Iago's suspicions. Othello then gets angry at Desdemona and then swears revenge against Desdemona and Cassio. Othello makes Iago his new lieutenant and orders him to kill Cassio.
Cassio give Bianca Desdemona's handkerchief to copy the embroidery of the handkerchief, not knowing that it is Desdemona's handkerchief.