Sahih Muslim Book - 13, Hadith - 2533

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِى شَيْبَةَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ إِدْرِيسَ عَنْ حُصَيْنٍ عَنِ الشَّعْبِىِّ عَنْ عَدِىِّ بْنِ حَاتِمٍ - رضى الله عنه - قَالَ لَمَّا نَزَلَتْ (حَتَّى يَتَبَيَّنَ لَكُمُ الْخَيْطُ الأَبْيَضُ مِنَ الْخَيْطِ الأَسْوَدِ مِنَ الْفَجْرِ) قَالَ لَهُ عَدِىُّ بْنُ حَاتِمٍ يَا رَسُولَ اللَّهِ إِنِّى أَجْعَلُ تَحْتَ وِسَادَتِى عِقَالَيْنِ عِقَالاً أَبْيَضَ وَعِقَالاً أَسْوَدَ أَعْرِفُ اللَّيْلَ مِنَ النَّهَارِ فَقَالَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- « إِنَّ وِسَادَتَكَ لَعَرِيضٌ إِنَّمَا هُوَ سَوَادُ اللَّيْلِ وَبَيَاضُ النَّهَارِ ».

It was narrated from Adiyy bin Hatim: “When the verse “Until the white thread appears to you distinct from the black thread of dawn”(Al-Baqarah 2:187) was revealed Adiyy [bin Hatim] said to him: ’O Messenger of Allah, I put to strings under my pillow, a white string and a black string, so that I can tell night from day.’ The Messenger of Allah (SAW) said: ‘Your pillow must be very big, for that refers to the blackness of the night and the whiteness of the day.’”