When Bassanio approaches Antonio for financial assistance in the play's first scene, Antonio—without yet knowing what Bassanio will ask for—assures his friend,
My purse, my person, my extremest means
Lie all unlocked to your occasions.
In other words, Antonio says that his money and even his very "person," or body, are at Bassanio's disposal. At first, these lines read as excessively generous and a hyperbolic, purely hypothetical offer for the sake of friendship (or, as some modern critics argue, romantic love).
But this is also a moment of vulnerability, and the audience could see Antonio's statement as too bold, or even dangerous, right off the bat. After all, Bassanio could well take advantage of his friend's generosity and choose to exploit him for his own selfish ends. Of course, this sentiment later reveals itself to be a clear example of foreshadowing when Antonio offers up his literal "person" as collateral for Shylock's loan, in the form of a "pound of flesh" that Shylock may cut from anywhere on Antonio's body—and not only offers it, but nearly sacrifices it in Act 4. So, Antonio's opening assurance to Bassanio isn't just an expression of friendly generosity, but a clue to the audience about the coming conflict.