What are some quotations in acts 3€“5 of Othello that show a character's deception of another character?

Shakespeare's is full
of deception. Iago is upset that Othello gave a promotion to Cassio instead of him, and so he
seeks to bring both of them down. In act three, his strategy is to plant seeds of jealousy and
doubt in Othello's mind. In scene three, Iago does not outright say that Desdemona is having an
affair with Cassio, but he suggests the possibility by asking about their relationship and
telling Othello to be careful:

Look to your wife; observe
her well with Cassio.

This is deceptive because Iago
knows that Desdemona is innocent, but he crafts his words carefully to make Othello suspicious
of his wife.

Iago's wife Emilia plays a part in the deception, although she
is not fully aware of consequences of her actions. Iago has told her he wants Desdemona's
handkerchief, so when Emilia picks it up off the ground, she decides to give it to her husband
instead of returning it to her lady.

I am glad I have
found this napkin:
This was her first remembrance from the Moor:
My wayward
husband hath a hundred times
Woo'd me to steal it; but she so loves the
token,
For he conjured her she should ever keep it,
That she reserves it
evermore about her
To kiss and talk to. I'll have the work ta'en out,
And
give't Iago: what he will do with it
Heaven knows, not I;
I nothing but to
please his fantasy.

Iago does not tell his intentions to
Emilia. If he had, she would not give him the handkerchief. Iago deceives his wife, and she
deceives Desdemona. In the following scene, Emilia pretends she does not know where the
handkerchief is:

Desdemona:
Where should I lose that handkerchief, Emilia?

Emilia:
I know not, madam.

Now that he has the
handkerchief, Iago is able to place it in Cassio's tent so Cassio will have it. Iago knows
Othello will see this as proof of the affair. Iago has Othello hide, while he talks to Cassio.
Iago talks to Cassio in a manner that to the overhearing Othello, it sounds like they are
speaking of Desdemona. But Cassio is also deceived by Iago, and is speaking of the camp follower
Bianca.

Iago: Ply Desdemona
well, and you are sure on't.
[Speaking lower]
Now, if this
suit lay in Bianco's power,
How quickly should you speed!

Cassio: Alas, poor caitiff!

Othello: Look, how he laughs already!

Iago: I never knew woman love man so.

Cassio: Alas, poor rogue! I think, i' faith, she loves
me.

Othello: Now he denies it faintly, and
laughs it out.

In act four, scene two, Othello confronts
Desdemona about her infidelity, and she tells the truth: that she is innocent. He is deceived,
and so he does not believe her. Desdemona seeks advice from Emilia and Iago. Although Iago has
orchestrated this whole lie, he pretends he knows nothing when talking to Desdemona:

Iago: What's the matter,
lady?

Emilia: Alas, Iago, my lord hath so
bewhored her.
Thrown such despite and heavy terms upon her,
As true hearts
cannot bear.

Desdemona: Am I that name,
Iago?

Iago: What name, fair lady?

Desdemona: Such as she says my lord did say I
was.

Emilia: He call'd her whore: a beggar in
his drink
Could not have laid such terms upon his callat.

Iago: Why did he so?

Desdemona: I do not know; I am sure I am none
such.

Iago: Do not weep, do not weep. Alas the
day!

Emilia: Hath she forsook so many noble
matches,
Her father and her country and her friends,
To be call'd whore? would
it not make one weep?

Desdemona: It is my
wretched fortune.

Iago: Beshrew him
for't!
How comes this trick upon him?

These are
just some quotes that show the web of Iago's deception.