What is being compared we saw three gallows black ravens in the book night?

In the book Night by Elie Wiesel, the comparison being made with the "three gallows black ravens" is to the three sinister-looking gallows that stood outside the Buna work camp. The gallows were a constant reminder of the arbitrary power of the Nazis and the ever-present threat of death that the prisoners faced. The comparison to black ravens adds an ominous and foreboding atmosphere, suggesting the lurking presence of death and the fragility of life in the camp.