´It was narrated from Khubaib bin 'Abdur-Rahman that his paternal aunt Unaisah said:` "The Messenger of Allah (S.A.W) said: 'When Ibn Umm Maktum calls the Adhan, eat and drink, and when Bilal calls the Adhan, do not eat nor drink."
Hadith Referenceسنن نسائي / كتاب الأذان / 641
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:إسناده صحيح