Did Fred and George ever tell anyone where they got the money?

Question

At the end of HP and the Goblet of Fire, Harry gives his winnings from the Triwizard Tournament to Fred and George so they can set up their joke shop. He also seems to want them not to tell anyone.

"Fred - George - wait a moment."
The twins turned. Harry pulled open his trunk and drew out his Triwizard winnings.
"Take it," he said, and he thrust the sack into George's hands.
"What?" said Fred, looking flabbergasted.
"Take it," Harry repeated firmly. "I don't want it."
"You're mental," said George, trying to push it back at Harry.
"No, I'm not," said Harry. "You take it, and get inventing. It's for the joke shop."
"He is mental," Fred said in an almost awed voice.
"Listen," said Harry firmly. "If you don't take it, I'm throwing it down the drain. I don't want it and I don't need it. But I could do with a few laughs. We could all do with a few laughs. I've got a feeling we're going to need them more than usual before long."
"Harry," said George weakly, weighing the money bag in his hands, "there's got to be a thousand Galleons in here."
"Yeah," said Harry, grinning. "Think how many Canary Creams that is." The twins stared at him.
"Just don't tell your mum where you got it... although she might not be so keen for you to join the Ministry anymore, come to think of it. . . ."
"Harry," Fred began, but Harry pulled out his wand.
"Look," he said flatly, "take it, or I'll hex you. I know some good ones now. Just do me one favour, OK? Buy Ron some different dress robes and say they're from you."

_{-- HP and the Goblet of Fire (emphasis mine)}

Given this air of secrecy, did the twins - or, for that matter, Harry - ever tell anyone else (such as Ron, Hermione, or Mrs Weasley) about this transaction? If not, how did they say they got the money to set up their joke shop?

Answer 1

Props to Kai who got there first.

Harry certainly confirms to Ron and Hermione in Harry Potter and the Order of the Phoenix that he gave Fred and George the gold.

(Context: This is just after Fred and George's post-swamp escape)

'It'll be my fault Fred and George left, you wait,' said Ron darkly. 'She'll say I should've stopped them leaving, I should've grabbed the ends of their brooms and hung on or something ... yeah, it'll be all my fault.'

...

'Yeah, but that's another thing, how did they get premises?' ... 'It's a bit dodgy, isn't it? They'll need loads of Galleons to afford the rent on a place in Diagon Alley. She'll want to know what they've been up to, to get their hands on that sort of gold.'

'Well, yes, that occurred to me, too,' said Hermione, ... 'I've been wondering whether Mundungus has persuaded them to sell stolen goods or something awful.'

'He hasn't,' said Harry curtly.

'How do you know?' said Ron and Hermione together.

'Because -' Harry hesitated, but the moment to confess finally seemed to have come. There was no good to be gained in keeping silent if it meant anyone suspected that Fred and George were criminals. 'Because they got the gold from me. I gave them my Triwizard winnings last June.'

...

But this is excellent!' said Ron, looking thrilled. 'It's all your fault, Harry - Mum can't blame me at all! Can I tell her?'

'Yeah, I suppose you'd better,' said Harry dully, ''specialy if she thinks they're receiving stolen cauldrons or something.'

-Harry Potter and the Order of the Phoenix - pp.599-600 - Bloomsbury - Chapter 30, Grawp

Whether Fred and George knew that Harry had told Ron and Hermione this isn't said. Nor is it said what their official line was. It also isn't confirmed whether Ron did tell Mrs Weasley or not.

Answer 2

By the beginning of The Order of the Phoenix, Harry assumes that Mrs Weasley doesn't yet know, and dreads what would happen if she found out:

Harry watched them go, feeling slightly uneasy. It had just occurred to him that Mr. and Mrs. Weasley would want to know how Fred and George were financing their joke shop business when, as was inevitable, they finally found out about it. Giving the twins his Triwizard winnings had seemed a simple thing to do at the time, but what if it led to another family row and a Percylike estrangement? Would Mrs. Weasley still feel that Harry was as good as her son if she found out he had made it possible for Fred and George to start a career she thought quite unsuitable? (OP9)

Answer 3

Also the Weasley twins tell Mundungus Fletcher when they get the Venomous Tentacula seeds in the chapter “The Woes of Mrs. Weasley,” that Harry is their financial backer:

Mundungus stopped talking when he saw Harry, but Fred winked and beckoned Harry closer.

”It’s okay,” he told Mundungus, “we can trust Harry, he’s our financial backer.”