She handed him a long, thin black quill with an unusually sharp point.
'I want you to write, I must not tell lies,' she told him softly.
'How many times?' Harry asked, with a creditable imitation of politeness.
'Oh, as long as it takes for the message to sink in,' said Umbridge sweetly. 'Off you go.'
She moved over to her desk, sat down and bent over a stack of parchment that looked like essays for marking. Harry raised the sharp black quill, then realised what was missing.
'You haven't given me any ink,' he said.
'Oh, you won't need ink,' said Professor Umbridge, with the merest suggestion of a laugh in her voice.
Harry placed the point of the quill on the paper and wrote: I must not tell lies.
He let out a gasp of pain. The words had appeared on the parchment in what appeared to be shining red ink. At the same time, the words had appeared on the back of Harrys right hand, cut into his skin as though traced there by a scalpel - yet even as he stared at the shining cut, the skin healed over again, leaving the place where it had been slightly redder than before but quite smooth.
Harry looked round at Umbridge. She was watching him, her wide, toadlike mouth stretched in a smile.
- Harry Potter and the Order of the Phoenix