Sunan Abi Dawud 2346
سنن أبي داود#2346SahihAddressing (the people) Samurah b. Jundub reported the Messenger of Allah (ﷺ) as saying:The adhan (call to prayer) of Bilal should not prevent you from taking a meal shortly before dawn, not does the whiteness of horizon (before dawn) in this way (vertically) until it spreads out horizontally
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (1094)
In-book reference: 14:34