"The admission is a precautionary measure, on the advice of His Royal Highness' Doctor."
The Daily Mail reports the prince had been "battling a flu-like illness for weeks" and suffered a fall before being rushed to hospital.
"The Duke has had a bad turn recently and has been looking much frailer of late," one source told Daily Mail.
"He's a remarkable man who has always prided himself on how robust he is, but he is six months off his 99th birthday and age takes its toll."
With Philip home in time for Christmas Day, the palace is no doubt breathing a sigh of relief. After all, Queen Elizabeth had to cancel some of the family's other annual traditional holiday activities due to his illness.