That he would steal away so guilty-like, Seeing you coming.
She did deceive her father, marrying you..fear your looks she loved them most.
I got him now
And so she did.
A good wench; give it me.
..she let it drop by negligence...took't up. Look here it is.
Iago plants the seed in Othello's mind that something is being hidden. This sparks doubt in Othello's mind that Iago knows something he does not want to reveal for it may be too harsh of a truth. This also sparks Othello's emotions in the matter right from the start and puts him exactly where Iago wants him. Iago can now take advantage of Othello's jealousy.
That in their sleeps will mutter their affairs...'Let us be wary, let us hide our loves...'
Using the handkerchief as his proof to bait Othello hook, line and sinker, Iago finalizes his clever plan. Iago makes it seem as if Cassio was in possession of the handkerchief so that it looks like he has a relationship with Desdemona behind the scenes. Then he goes on to explain that he overheard Cassio talking about a sexual encounter with Desdemona in his sleep. To solidify and completely convince Othello, Iago says that men like Cassio often reveal secrets like their affairs in their sleep. This drives Othello crazy and sends his thoughts wild.