"I'll poison his delight."
Iago says this to Roderigo in the opening of the film. As these lines make unmistakable, it is Iago's desire to poison Othello through his relationship with Desdemona.
"I have but an hour of love to spend with thee. We must obey the time."
Othello says this to Desdemona before having to set off. His words tell us the deep love he experiences for Desdemona that he desires to express, as he cannot hold them off.
"Honest my lord?"
Othello asks Iago if Cassio is honest, and Iago responds with a question as though he is innocent in the matter, when in fact he is setting Othello up for tragedy. Iago is leading Othello to believe that Cassio is sleeping with his, Othello's own, wife.