"The one with the power to vanquish the Dark Lord approaches...Born to those who have thrice defied him, born as the seventh month dies...and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not...and either must die at the hand of the other for neither can live while the other survives...." —Prophecy made to Albus Dumbledore by Sibyll Trelawney
The prophecy above was made to Albus Dumbledore by Sibyll Trelawney and foretold the coming of a boy who would have the power to vanquish Lord Voldemort. The prophecy was made while Dumbledore was giving an interview to Trelawney for the post of Divination Teacher at Hogwarts School of Witchcraft and Wizardry. Dumbledore, who was disappointed at the performance she gave during the interview, was about to leave when she went into a trance and made the prophecy.
Dumbledore made a great effort to keep Trelawney at Hogwarts to protect her from Voldemort. She had no memory of what she had said.