Ibn 'Abbaas Radiyallahu 'Anhu reports:
"Once Rasulullah Sallallahu 'Alayhi Wasallam slept and began snoring. It was, the nature of Rasulullah Sallallahu 'Alayhi Wasallam that he snored, when he slept. Bilaal Radiyallahu 'Anhu gave the call to prepare for salaah. Rasulullah Sallallahu 'Alayhi Wasallam awakened and performed the salaah. He did not perform the wudu". This hadith has a detailed incident
English reference: Book 38, Hadith 245
Arabic reference: Book 39, Hadith 258