Prayer (Kitab Al-Salat)

Dawud :: Book 2 : Hadith 532

Narrated Abdullah ibn Umar:

Bilal made a call to prayer before the break of dawn; the Prophet (peace_be_upon_him), therefore, commanded him to return and make a call: Lo! the servant of Allah (i.e. I) had slept (hence this mistake).

The version of Musa has the addition: He returned and made a call: Lo! the servant of Allah had slept.