Slaughterhouse Five

Vonnegut uses the popular Christmas carol, Away in the Manger, as his epigraph.

Which is why the epigraph of this book is the quatrain from the famous Christmas carol. Billy cried very little, though he often saw things worth crying about, and in that respect, at least, he resembled the Christ of the Carol:
The cattle are lowing,
The Baby awakes.
But the little Lord Jesus
No crying He makes.