“He was the on’y man for the job,” said Hagrid, offering them a plate of treacle toffee, while Ron coughed squelchily into his basin. “An’ I mean the on’y one. Gettin’ very difficult ter find anyone fer the Dark Arts job. People aren’t too keen ter take it on, see. They’re startin’ ter think it’s jinxed. No one’s lasted long fer a while now.”
About Gilderoy Lockhart

Harry Potter and the Chamber of Secrets - Chapter 7 : Mudbloods and Murmurs
See this quote in the Pensive -