I had assumed that it was common knowledge that Bin Laden denied any involvement in the 9/11 attacks. In a few seconds, though, a Google search can remind us of that fact. Here is an example from the top of the result list of my own Google search:

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USA Today, September 12, 2001
Saudi dissident Osama bin Laden congratulated the people who carried out the deadly terrorist strikes in the United States, but denied Wednesday that he was involved, a Palestinian journalist said. “Osama bin Laden thanked Almighty Allah and bowed before him when he heard this news,” Jamal Ismail, Abu Dhabi Television’s bureau chief in Islamabad, said, quoting a close aide of bin Laden’s. Ismail said the aide, whom he wouldn’t identify by name, called him early Wednesday on a satellite telephone from a hide-out in Afghanistan. Bin Laden praised the people who carried out the attacks in Washington and New York, Ismail said, quoting the aide. “But he had no information or knowledge about the attack” ahead of time, Ismail said.
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http://www.usatoday.com/news/world/2001/09/12/binladen-happy.htm