[Fai Mao]

And how did Kahn know a Klingon proverb when he had never met a Klingon?

[Flick Lives]

And how did Kahn know a Klingon proverb when he had never met a Klingon?

—

In the TOS episode “Space Seed”, after Kahn is revived from cryosleep, he’s invited by Kirk to read from the ship’s library during his convalescence. Being an augmented human, Kahn reads everything, which is how he then is able to take over the ship. The ship’s library no doubt included extensive info on Klingons as the Federation had already fought them during the Earth Klingon War.

[BlackbirdSST]

And how did Kahn know a Klingon proverb when he had never met a Klingon?

He read everything on the Enterprise computers in about 1:45 minutes.