Fasting
30/50. Chapter:
To observe Saum continuously day and night (Al-Wisal) till the time of Sahar.
Sahih Bukhari
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 ".
Narrated Abu Sa`id Al-Khudri: 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."
Reference : Sahih al-Bukhari 1967In-book reference : Book 30, Hadith 74USC-MSA web (English) reference : Vol. 3, Book 31, Hadith 188