"Because you will learn nothing staying here." And he needs to obtain his focus if he's to do anything he wanted to upon waking. There's the matter of preserving the body however. The way the elves used to preserve bodies, preparing them for their long sleep, may not be applicable here. How would those techniques affect a human corpse? Or at least, he's assuming it's a human corpse.

"Our preservation methods differ. Where do you keep the body?"