'It's going to be all right, sir,' Harry said over and over again, more worried by Dumbledore's silence than he had been by his weakened voice. 'We're nearly there... I can Apparate us both back... don't worry...'
'I am not worried, Harry,' said Dumbledore, his voice a little stronger despite the freezing water. 'I am with you.'
J.K. Rowling - Harry Potter and the Half-Blood Prince