The Messenger of Allah ﷺ said, "Eat and drink, and do not let the rising vertical light alarm you. Keep eating and drinking until the red light spreads horizontally across the horizon."
قال رسول الله ﷺ: كلوا واشربوا، ولا يهيدنكم الساطع المصعد، فكلوا واشربوا حتى يعترض لكم الأحمر.
Narrated by Abu Dawud (2348), Tirmidhi (705), and Ibn Khuzayma (1930), all through the route of Mulazim bin Amr, from Abdullah bin Numan, who said, Qays bin Talq narrated to me, from his father, and so on as mentioned. Tirmidhi said, "This is a hasan gharib hadith by this route." Ibn Khuzayma said, "The proof that the second Fajr which we have described is the whiteness that spreads across the horizon with a reddish color, is contingent on this report being sound, for I do not know this Abdullah bin Numan by any judgment of reliability or discredit, nor do I know of any narrator from him other than Mulazim bin Amr."I say, as for the first objection, namely his statement, "I do not know Abdullah bin Numan by any judgment of reliability or discredit," the endorsement of Ibn Main for him has already been established, as Ajli and Ibn Hibban also endorsed him as reliable. This also refutes Hafiz's statement in Taqrib, "acceptable," for at the very least he is "truthful."As for the second objection, namely his statement, "I do not know of any narrator from him other than Mulazim bin Amr," Umar bin Yunus also narrated from him, as mentioned by Ibn Abu Hatim in Jarh wa Tadil, and by Hafiz in Tahdhib al-Tahdhib. Likewise, Muhammad bin Jabir also narrated from him. Imam Ahmad narrated it (16291) from Musa, from him, from Abdullah bin Numan, from Qays bin Talq, from his father, that the Prophet ﷺ said, "The Fajr is not the one that stretches lengthwise across the horizon, but rather the one that spreads across it in red." However, Muhammad bin Jabir, who is Ibn Sayyar bin Tariq Hanafi Yamami, is daif, though Hafiz said, "truthful," and said, "Abu Hatim ranked him above Ibn Lahia." He has been corroborated as shown in the preceding chains.The hadith has another route through Mulazim bin Amr, who said, Abdullah bin Badr Suhaymi narrated to us, who said, my grandfather Qays bin Talq narrated to me, who said, my father narrated to me, that the Prophet of Allah ﷺ said, (and he related the hadith similarly to the hadith of Abu Dawud). Tahawi narrated it in his Sharh (2/107) from Abu Umaya, who said, Abu Naeem and Khadr bin Muhammad bin Shujaa narrated to us, both from Mulazim bin Amr, with his chain of transmission. Abdullah bin Badr Suhaymi Hanafi is "reliable," among the narrators of the Sunan.Taking all these chains together, this hadith is sahih or hasan. Tirmidhi said, "The practice among the people of knowledge is that eating and drinking are not forbidden to the fasting person until the red Fajr spreads across the horizon. This is the view held by the majority of the people of knowledge."