Sahih Bukhari, Chapter: Prayer at Night (Tahajjud)

That once Allah's Apostle (p.b.u.h) said, "Your brother, i.e. 'Abdullah bin Rawaha does not say obscene (referring to his verses): Amongst us is Allah's Apostle, who recites His Book when it dawns. He showed us the guidance, after we were blind. We believe that whatever he says will come true. And he spends his nights in such a way as his sides do not touch his bed. While the pagans were deeply asleep."