Harry laid down his knife and fork, his heart beating rather fast considering that all he was doing was sitting in bed. Dumbledore said to do it... why not now?
He fixed his eyes on his fork, which was gleaming in the sunlight streaming on to his lap, and said, "I don't know exactly why he's going to be giving me lessons, but I think it must be because of the prophecy."
Neither Ron nor Hermione spoke. Harry had the impression that both had frozen. He continued, still speaking to his fork, "You know, the one they were trying to steal at the Ministry."
"Nobody knows what it said, though," said Hermione quickly. "It got smashed."
"Although the Prophet says -" began Ron, but Hermione said, "Shhh!"
"The Prophet's got it right," said Harry, looking up at them both with a great effort: Hermione seemed frightened and Ron amazed. "That glass ball that smashed wasn't the only record of the prophecy. I heard the whole thing in Dumbledore's office, he was the one the prophecy was made to, so he could tell me. From what it said," Harry took a deep breath, "it looks like I'm the one who's got to finish off Voldemort... at least, it said neither of us could live while the other survives."
The three of them gazed at each other in silence for a moment.

Harry Potter and the Half-Blood Prince
Chapter 5, An Excess of Phlegm
by J.K. Rowling