It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Fajr (dawn) is of two kinds: a fajr in which eating is permissible and prayer is forbidden, and a fajr in which prayer is permissible and eating is forbidden."
Abu Ahmad narrated it thus as musnad (attributed to the Prophet), while others narrated it as mawquf, and the mawquf is more correct.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1767