It should be a text written by the German Protestant priest Martin on the Jewish Memorial in Boston, USA:
At first they hunted down the communists. I was not a communist. I kept silent; then they went after the Jews, and I was not a Jew, so I kept silent; then they went after the trade unionists, and I was not a trade unionist, and I continued to keep silent; then they went after the Catholics, and I was not a Catholic, and I still kept silent. ;Finally, they came to me, and no one stood up to speak for me anymore.