Provide a quote of racism in Othello.

From the text:

IAGO:
Even now, now, very now, an old black ram
Is tupping your white ewe. Arise, arise!
Awake the snorting citizens with the bell,
Or else the devil will make a grandsire of you.
Arise, I say! (1.1.97-101)

DUKE OF VENICE:
And, noble signior,
If virtue no delighted beauty lack,
Your son-in-law is far more fair than black. (1.3.328-331)