A reader supplies it: “Hell, I’ll kill a man in a fair fight… or if I think he’s gonna start a fair fight, or if he bothers me, or if there’s a woman, or if I’m gettin’ paid – mostly only when I’m gettin’ paid…”
Another noteworthy Jayne line comes in that episode of Firefly where the crew are debating whether to go help some damsels in distress on a nearby planet. I can’t locate the lines, but it’s something like:
JAYNE: Why should we be helpin’ these folk? We don’t know them. They’re nothing to us.
MAL: They’re whores.
JAYNE: I’m in.