Sahih al-Bukhari 1967
Sahih al-Bukhari · Book 30: Fasting · To observe Saum continuously day and night (Al-Wisal) till the time of Sahar.
Narrated Abu Sa`id Al-Khudri:
حَدَّثَنَا إِبْرَاهِيمُ بْنُ حَمْزَةَ ، حَدَّثَنِي ابْنُ أَبِي حَازِمٍ ، عَنْ يَزِيدَ ، عَنْ عَبْدِ اللَّهِ بْنِ خَبَّابٍ ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ـ رضى الله عنه ـ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " لاَ تُوَاصِلُوا، فَأَيُّكُمْ أَرَادَ أَنْ يُوَاصِلَ فَلْيُوَاصِلْ حَتَّى السَّحَرِ " . قَالُوا فَإِنَّكَ تُوَاصِلُ، يَا رَسُولَ اللَّهِ. قَالَ " لَسْتُ كَهَيْئَتِكُمْ، إِنِّي أَبِيتُ لِي مُطْعِمٌ يُطْعِمُنِي وَسَاقٍ يَسْقِينِ ".
Allah's Messenger (ﷺ) said, "Do not fast continuously day and night (practice Al-Wisal) and if anyone of you intends to fast continuously day and night, he should continue till the Suhur time." They said, "But you practice Al-Wisal, O Allah's Messenger (ﷺ)!" The Prophet (ﷺ) said, "I am not similar to you;. during my sleep I have One Who makes me eat and drink."