The Meaning of Allah, the Most High's saying "And eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)"
أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مُطَرِّفٍ، عَنِ الشَّعْبِيِّ، عَنْ عَدِيِّ بْنِ حَاتِمٍ، أَنَّهُ سَأَلَ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ قَوْلِهِ تَعَالَى { حَتَّى يَتَبَيَّنَ لَكُمُ الْخَيْطُ الأَبْيَضُ مِنَ الْخَيْطِ الأَسْوَدِ } قَالَ " هُوَ سَوَادُ اللَّيْلِ وَبَيَاضُ النَّهَارِ " .
It was narrated from 'Adiyy bin Hatim that: he asked the Messenger of Allah (ﷺ) about the verse "Until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)." He said: "It is the blackness of the night and the whiteness of the day." '