Yahya related to me from Malik that he had heard that themuadhdhin came to Umar ibn al-Khattab to call him to the subh prayerand found him sleeping, so he said, "Prayer is better than sleep," andUmar ordered him to put that in the adhan for subh .
App reference: Book 3, Hadith 8
USC-MSA web (English) reference: Book 3, Hadith 8
Arabic reference: Book 3, Hadith 154