From Sahih Bukhari (Hadith 1918):
Narrated `Aisha:Bilal used to pronounce the Adhan at night, so Allah's Messenger (ﷺ)? said, "Carry on taking your meals (eat and drink) till Ibn Um Maktum pronounces the Adhan, for he does not pronounce it till it is dawn
Reference: Bukhari 1918