The Prophet (peace and blessings be upon him) said:
"Indeed, Bilal gives the adhan at night in order to wake those of you who are asleep and to send back those of you who are standing in prayer (tahajjud) (for the pre-dawn meal)."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 2041
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[ن] عن ابن مسعود. الإرواء ٢١٩: حم، ق، د.