Al-Kāfi #1048“Abu ‘Abd Allah (a.s.), has said, ‘Dawn is when you find a white line like the whiteness of Sur 5 (a certain section of Euphrates river in...
Man Lā Yaḥḍuruh al-Faqīh #1431"The true Fajr (dawn) is the one that, when you see it, appears spread out horizontally, like the whiteness of the Surā river."