In chapter 3 of the novel Nightby Elie Wiesel, we find the narrator walking through the path of cremation closely followed by his father. At this point the reality has sunk in: They are witnessing children being burned alive, as well as babies. This is a horrific moment that even brings Wiesel's father to tears.
It is at this precise time when Wiesel considers throwing himself at the barbed wire, since it would electrocute him faster and less painfully than the roasting fire. Since the men truly feel that they are about to be burned alive, some begin to sing the Jewish song of death, the Kaddish.
The irony of using the Kaddish: First, the Kaddish is sung by the mourner for the dead. In other cases, it is a song a strictly to be employed by the Rabbi.In this case, the men are singing the song on their own behalf. This means that they are either seeing themselves already as dead men walking, or that they feel as if the only mercy on them will come from their own hearts.
Either way, Ellie does not say the Kaddish. At this point, he stops believing in God. He has decided that God has left him at their own mercy. He does not feel it is fair to as mercy from Him.