fluffy,
Mudhen is correct: The money-owing line is by Ruark, not Capstick--but just about everything written about Cape buffalo since has quoted or stolen the line, to the point where it almost HAS to be used, even though it's become something of a cliche.
It's something like writing about the 7x57 without mentioning Bell and his elephants: If you don't, some reader will feel compelled to "correct" your apparent ignorance, so it has to be thrown in there.
