I, Balin Fergusson, record these words in the event I should die, for I wish to be recognized by name. It is the fourth day since I hid in this branch of the shaft. Separated from the monsters by traps, I am safe, but how long will I survive without water? I have the key to the storeroom and can think of nothing else than to sneak there quietly to get provisions. Reason, however, tells me the storeroom is too far and I won't be able to make it. The monsters are trying to reach me again, so I have to wait anyway. Later, when I'm desperate, who knows?
The Balin's Journal quest item that you can find in the mines is a clear reference to The Lord of the Rings. While exploring the mines of Moria, the Fellowship finds "The Book of Khazad-dùm" written by Balin before he died in Moria, where he was buried.