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?