"Circe, Circe,
how dare you tell me to treat you with any warmth?
You who turned my men to swine in your own house and now
you hold me here as well – teeming with treachery
you lure me to your room to mount your bed,
so once I lie there naked
you’ll unman me, strip away my courage!
Mount your bed? Not for all the world. Not
until you consent to swear, goddess, a binding oath
you’ll never plot some new intrigue to harm me."
Straightaway
she began to swear the oath that I required – never,
she’d never do me harm – and when she’d finished,
then, at last, I mounted Circe’s gorgeous bed.

– Homer

The Odyssey, Book 10, lines 373-385. Odysseus shows his cunning in this reply to the temptress witch Circe when she asks him to share her bed for "the magic work of love." He demands that the powerful goddess swear a solemn oath never to plot any harm against him. She agrees and only after that does he share her bed.