Sahih al-Bukhari 620
صحيح البخاري#620SahihNarrated `Abdullah bin `Umar:Allah's Messenger (ﷺ) said, "Bilal pronounces the Adhan at night, so keep on eating and drinking (Suhur) till Ibn Um Maktum pronounces the Adhan
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 10:18