Why is it, in the book Night, that Elie Wiesel could have wept with rage when his father begs for rest upon arrival at Buchenwald ?

By the time
Elie and his father arrive at Buchenwald, Elie has been fighting to keep them together and alive
for a long time. He is again faced with the task of trying to guide both of them through the
processing that was necessary before they could go to sleep. Elie's father, however, was too
exhausted physically and too tired mentally to continue the battle. He was ready to give up.
"I can't anymore...It's over...I shall die right here..."

To Elie,
this was unacceptable. He had worked too hard, had made too many sacrifices in order to keep his
father with him and to protect him so that he could stay alive. For his father to now wish to
die was beyond Elie's capacity to understand and allow - it was infuriating.

To have lived and endured so much; was I going to let my father die
now?...I knew that I was no longer arguing with him but with Death itself, with Death that he
had already chosen.

Elie's anger with his father and with
their situation enraged him. His response was to weep with anger and frustration and
exhaustion.