Hadith 14:37
Narrated 'Adi b. Hatim:
When the verse "Until the white thread of dawn appear to you distinct from its black thread" was revealed, I took a white rope and a black rope, and placed them beneath my pillow ; and then I looked at them, byt they were not clear to me. So I mentioned it to the Messenger of Allah (ﷺ). He laughed and said: Your pillow is so broad and lengthy ; that is (i.e. means) night and day. The version of the narrator 'Uthman has: That is the blackness of night and whiteness of day.
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا حُصَيْنُ بْنُ نُمَيْرٍ، ح وَحَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا ابْنُ إِدْرِيسَ، - الْمَعْنَى - عَنْ حُصَيْنٍ، عَنِ الشَّعْبِيِّ، عَنْ عَدِيِّ بْنِ حَاتِمٍ، قَالَ لَمَّا نَزَلَتْ هَذِهِ الآيَةُ حَتَّى يَتَبَيَّنَ لَكُمُ الْخَيْطُ الأَبْيَضُ مِنَ الْخَيْطِ الأَسْوَدِ قَالَ أَخَذْتُ عِقَالاً أَبْيَضَ وَعِقَالاً أَسْوَدَ فَوَضَعْتُهُمَا تَحْتَ وِسَادَتِي فَنَظَرْتُ فَلَمْ أَتَبَيَّنْ فَذَكَرْتُ ذَلِكَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فَضَحِكَ فَقَالَ " إِنَّ وِسَادَكَ لَعَرِيضٌ طَوِيلٌ إِنَّمَا هُوَ اللَّيْلُ وَالنَّهَارُ " . قَالَ عُثْمَانُ " إِنَّمَا هُوَ سَوَادُ اللَّيْلِ وَبَيَاضُ النَّهَارِ " .
Original Reference: Sunan Abi Dawud 2349