It wasnarrated from 'Abdullah bin Mas'ud that the Messenger of Allah(ﷺ) said:
"The Adhan of Bilal should not prevent anyone of youfromeating Suhur, for he gives the Adhan to alert those among youwho areasleep, and so that anyone who is praying can prepare himselfforfasting. The Fajr does not come in this manner, rather it comesinthis manner, and it appears along the horizon."
English reference: Vol. 1, Book 7, Hadith 1696
Arabic reference: Book 7, Hadith 1766