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”"
SahihSahihIsnaad SahihBook 7 · Hadith 15