Not to mention that Rura Penthe is a Klingon prison. LOL
Actually (and I got this slightly wrong before, I was remembering from a different film and thinking it was said to Chekov), but the actual line is:
"Pray, Mr. Saavik, the Klingons don't take prisoners".
I always took it to mean, pray as in hope. Hope they kill you instead if taking you prisoner because being taken prisoner by Klingons is not a nice thing. As in, he thought in the way Lorca did when killing his crew.
The actual line is:
Saavik: "Any suggestions, Admiral?"
Kirk: "Prayer, Mr. Saavik. The Klingons don't take prisoners."
It's a definitive statement.
Which is disproven by the constant taking of prisoners they keep doing, putting them on trial, and having prisons for them. Since before Enterprise, and all the way through to Nemesis.
Kirk was trying to scare her, using a blatantly false statement.
Actually, it goes like this:
Saavik: Any suggestions, Admiral?
Kirk: Prayer, Mr. Saavik. The Klingons don't take prisoners.
Kor
I always took this "no prisoners" thing as propaganda. There are so many instances of the Klingons actually taking prisoners that it can't be taken literally. Since the dealings with the Klingons are so often used as allegory for contemporary conflicts, it seems like this and other instances of dehumanization, such as the overt racism shown towards the Klingons in Star Trek VI, are attempts to call attention to how real soldiers are taught to see their enemies as less than human to make it easier to kill them.