Sayyiduna Ibn Abbas (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Dawn is of two kinds: the first neither makes food forbidden nor makes the prayer lawful; but the second dawn makes food forbidden and makes the prayer lawful."
Abu Ahmad al-Zubayri narrated it as a saying of the Prophet, while others narrated it from al-Thawri as mawquf (a statement of Ibn Abbas).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8003