It is narrated from Muhammad bin Abd al-Rahman bin Thawban (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) said: "Fajr (dawn) is of two kinds," and the rest of the hadith is the same. (It has also been narrated through another chain as marfu' and as mawquf.)
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1766