Sam immediately sets the flogger aside, moving to Castiel's side and wrapping his arm around the other man's waist. The area has far too many organs to be considered useful for flogging, so it's also a safe spot for him to put his arm, to help take the weight so that Castiel doesn't hurt himself.

"Cas, no," he says softly, reaching up to wipe the hair from Castiel's forehead. "That's enough." It was obviously more than enough. "I'm calling it. My safe word is Lucifer and that's it, Cas. No more."