"One way or another he has to say 'I want to leave' or 'I want to stay'," said Mourinho.
Rooney's Premier League goals
"The person that started the story has to finish the story. For the good of everyone, it is time to finish the story."
Mourinho suggested the 27-year-old striker himself was the catalyst for Chelsea's move saying "he told someone very important in his career" that he wanted to leave United.
Asked how long he was prepared to wait before moving on to other targets - with Anzhi Makhachkala's Cameroon striker Samuel Eto'o understood to be the alternative - Mourinho replied: "Twenty-four hours, 48 hours."
He continued: "If you look at a manager like me, a club like us and the people who work at the club with me, we are not silly enough to try to get a player from a big club that doesn't want to sell.
"We are not silly enough to try something if somebody didn't start it."
He added: "After that, if he wants to leave he has to say - or if he has decided now he doesn't want to leave any more then he has to say."
The former Everton forward was given huge support throughout by United's fans - and indeed by Chelsea's supporters who want him to switch to Stamford Bridge.
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