I have frequently come across Kronecker's statement about set theory:
I don't know what predominates in Cantor's theory - philosophy or theology, but I am sure that there is no mathematics there.
It is quoted in Wikipedia. Google shows over 400 hits. But I have never seen a hint to the original source.
It need not be explained that Kronecker had a very negative attitude toward set theory. Did Kronecker say so? And if yes, where and when?