Night is the story of Eliezer's time in Auschwitz during WWII. Elie goes into great detail about the horrors that the Jews experienced at the hands of the Nazi army. Elie says in the book that there is only one person who has kept his promise. Elie says that Hitler is the one person that actually kept his word to the Jewish people.
It is quite interesting that Elie would say this about Hitler, but when you read Night, you realize the context in which Elie is saying this. Elie is saying that in his time at Auschwitz, the one person who did what they said they were going to do was Hitler. Hitler said that his intention was to eliminate all Jews, and he almost accomplished this. Elie knew that. He was well aware of the fact that Hitler was the one person who was reliable to do what he said he was going to do.
Elie's hate for Hitler didn't change the way he felt about him. He knew that, given the time and the chance, Hitler would have done anything to finish his work. Elie lost his faith in God while at the concentration camp, but he knows now that it was by the Grace of God that he is still alive. Hitler was a maniac that got away with horrible crimes against humanity, but Elie survived and went on to tell the whole world about the horrors that happened. And thanks to Elie, we will never forget. Never.