How does Scrooge behave with his nephew before the ghost has transformed his heart in A Christmas Carol?

Scrooge will not suffer his nephew's good cheer when he comes to visit his uncle's office.
When Fred, Scrooge's jovial nephew, visits his uncle, he calls out swiftly as he enters, "A merry Christmas, uncle! God save you!"

"Bah!" said Scrooge. "Humbug!"

Fred is astonished. "Christmas a humbug, uncle!....You don't mean that, I am sure?" Scrooge assures his nephew that he does, indeed, mean exactly that. He asks Fred for what reason he is happy because he is "poor enough." To this remark, Fred cleverly turns his uncle's question back upon him as he asks his Uncle Ebeneezer what right he has to be so gloomy and morose. "You're rich enough."
Having nothing else to express himself, Scrooge reiterates, "Humbug!...What is Christmas to you but a time to pay bills without the money?" Then, even though his nephew tries to cajole him into a more cheerful mood, Scrooge continues to rant, arguing that he will keep Christmas as he pleases; after all, it has not done Fred any good.Fred tells his uncle that all things cannot be measured by monetary profit. Christmas is, to Fred,

...a good time...a kind, forgiving, charitable, pleasant time: the only time... when men and women seem by one consent to open their shut-up hearts freely, and to think of people below them as if they really were fellow-passengers to the grave, and not another race of creatures bound on other journeys.

Hearing this pronouncement of the merits of Christmastime, Bob Crachit applauds from the other room. Embarrassed that he has demonstrated the impropriety of listening, Bob quickly goes about stoking his pitiful fire from one lonely coal. Scrooge shouts out a threat to fire him if he hears anything else, adding, "I wonder you don't go into Parliament!" alluding to the vocal exchanges among those in this office.
Despite Scrooge's harsh and cruel words, Fred invites his uncle to Christmas dinner at his home. But, Scrooge declines, saying sharply, "Good afternoon!"
This early scene in the novella of Dickens serves to characterize Ebenezer Scrooge as a cold, heartless, materialistic old curmudgeon.