In chapter 8 of Night, why was Elie's father being beaten?

In section eight of Night, Elie's father is very ill. He has dysentery and is so weak that he can't get out of bed. Elie tries to ignore his father's cries, but his guilt gives way to him feeling sorry for his father. He gives his father water and some soup, and feels mad, because he wants to keep the food for himself to keep up his strength. Elie struggles with his own guilt over his feelings towards his father. 

The guard tells Elie that death is not far away, and there is nothing else anyone can do for him. Elie's father cries out to the guard for some water, and the guard yells at him to stop, then goes about beating him on the head. The next morning, Elie wakes and finds out that his father has died and was taken to the crematorium. It was Jan, 29, 1945, not many days until they were to be liberated. Elie feels bad that all he feels is relief now that his father has died.

Elie goes through many different emotions while being a prisoner. The Nazis had stripped the Jews of all their identity, and they took away their ability to feel anything. They had all stopped feeling anything. Elie had stopped feeling the father and son bond, and looked at his father as an obstacle now. With his death, Elie thinks he will be free to just think about himself now, and not have to worry about his father. Little does he realize that these memories will stay with him the rest of his life. He will never be able to forget them, and through his work, we will never be able to forget them, either.