Quote 1
SHYLOCK [aside]
How like a fawning publican he looks!
I hate him for he is a Christian,
But more for that in low simplicity
He lends out money gratis and brings down
The rate of usance here with us in Venice.
If I can catch him once upon the hip,
I will feed fat the ancient grudge I bear him.
He hates our sacred nation, and he rails,
Even there where merchants most do congregate,
On me, my bargains and my well-won thrift,
Which he calls "interest." Cursed be my tribe
If I forgive him! (1.3.41-52)
There's no love lost between Shylock and Antonio. Shylock insists that he hates Antonio because he's a "Christian" and because he undermines his money-lending business and talks smack about him at the Rialto (the merchant's exchange in Venice). We also learn that Antonio hates Shylock's "sacred nation," and we'll soon learn just how much of an anti-Semite Antonio is.
Quote 2
SHYLOCK
This kindness will I show.
Go with me to a notary, seal me there
Your single bond; and in a merry sport,
If you repay me not on such a day,
In such a place, such sum or sums as are
Express'd in the condition, let the forfeit
Be nominated for an equal pound
Of your fair flesh, to be cut off and taken
In what part of your body pleaseth me.
ANTONIO
Content, in faith. I'll seal to such a bond,
And say there is much kindness in the Jew. (1.3.155-165)
Shylock's business proposition is associated with a racist stereotype. When he suggests that a pound of Antonio's "fair flesh" should serve as a bond for the loan, Shakespeare's 16th-century audience would have been reminded of the (completely false) stories about murderous Jews who supposedly sought Christian blood for use in religious rituals.
Quote 3
SHYLOCK
You call me misbeliever, cutthroat dog,
And spet upon my Jewish gaberdine,
[...]
'Fair sir, you spet on me on Wednesday
last,
You spurned me such a day; another time
You called me dog; and for these courtesies
I'll lend you thus much moneys'?
ANTONIO
I am as like to call thee so again,
To spit on thee again, to spurn thee too. (1.3.121-122; 135-141)
Yikes! When Shylock points out that Antonio has treated him like garbage, Antonio is unapologetic and insists that his racist behavior will never change, not even if Shylock lends him money. When we read passages like this, we wonder whether Antonio's abuse of Shylock is at least partially to blame for our "villain's" treacherous behavior later in the play.