** Gollum

And what would you swear?' asked Frodo.
'To be very good,' said Gollum. Then crawling to Frodo's feet he grovelled before him, whispering hoarsely: a shudder ran over him, as if the words shook his very bones with fear. 'Smeagol will swear never, never, to let Him have it. Never! Smeagol will save it. But he must swear on the Precious.' --

TTT, "The Taming of Smeagol"