In Shakespeare's play, The Merchant of Venice, the audience should not believe Shylock's expression of friendship in his shaking of Antonio's hand.
There is no question that there is "bad blood" between Antonio and Shylock. And Antonio would not be with Shylock to borrow money if he had his own money to give to Bassiano.
Shylock's "aside" in Act One, scene three, makes this crystal clear.
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.(40) 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,(45) Which he calls interest. Cursed be my tribe If I forgive him!
As Shylock speaks so only the audience can hear him ("aside"), the audience learns how Shylock really feels about Antonio.
First Shylock says he hates Antonio because he is a Christian. The other reason the money lender hates him is because Antonio lends money to those in need without charging interest ("gratis"). This infuriates Shylock because when Antonio makes a loan without charging interest, the interest rates in town go down, and in essence, Shylock makes less money. He is a greedy man, and in his opinion, Antonio takes the food out of his mouth in doing so.
Shylock also admits that if he could beat Antonio just one time, he would be able to exact his revenge for the "harm" he feels Antonio has visited upon him. He accuses Antonio for hating Shylock because he is a Jew, and says that Antonio criticizes Shylock in public for charging interest—the way Shylock makes his money. Shylock closes his aside by saying that his tribe would be cursed before Shylock would forgive him.
With all of this in mind, the audience would do best to ignore Shylock's empty gesture of friendship: the man does not know the meaning of the word.