I heard the Messenger of Allah ﷺ say, "Do not let any of you be deceived by Bilal's call from taking the predawn meal, nor by this whiteness until it spreads across the sky."In another narration, "Let neither Bilal's call to prayer nor the elongated dawn prevent you from your predawn meal, but rather the dawn that spreads across the horizon."
سمعت رسول الله ﷺ يقول: لا يغرن أحدكم نداء بلال من السحور، ولا هذا البياض حتى يستطير. وفي رواية: لا يمنعنكم من سحوركم أذان بلال، ولا الفجر المستطيل، ولكن الفجر المستطير في الأفق.
The first narration was reported by Muslim in the chapter on fasting (1094) through several routes from Abdullah bin Suwada Qushayri, from his father, from Samura bin Jundab. In the narration of Shuba, from Suwada, with this same chain, the wording is, "Do not be deceived by Bilal's call, nor by this whiteness, until dawn appears," or he said, "until Fajr breaks forth." Nasai also reported it through this same route (2171), and he said, Abu Dawud (Tayalisi) said, on the authority of Shuba, "and he spread his hands to the right and left."The second narration was reported by Tirmidhi (706) through the route of Abu Hilal, from Suwada, with this same chain. Abu Dawud also reported it (2346) through the route of Hammad bin Zayd, from Abdullah bin Suwada, with this same chain, and its wording is, "Let not Bilal's call to prayer keep you from your pre-dawn meal, nor the whiteness on the horizon that appears like this, until it spreads across the sky."