Language:
كتاب التهجد
19  
Prayer at Night (Tahajjud)
(9)
Chapter: To prolong the standing posture in the Tahajjud
(9)
باب طُولِ الْقِيَامِ فِي صَلاَةِ اللَّيْلِ
Sahih al-Bukhari 1135

Narrated Abu-Wail:

`Abdullah said, "One night I offered the Tahajjud prayer with the Prophet (ﷺ) and he kept on standing till an ill-thought came to me." We said, "What was the ill-thought?" He said, "It was to sit down and leave the Prophet (standing)."

حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ قَالَ صَلَّيْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم لَيْلَةً، فَلَمْ يَزَلْ قَائِمًا حَتَّى هَمَمْتُ بِأَمْرِ سَوْءٍ‏.‏ قُلْنَا وَمَا هَمَمْتَ قَالَ هَمَمْتَ أَنْ أَقْعُدَ وَأَذَرَ النَّبِيَّ صلى الله عليه وسلم‏.‏
Reference : Sahih al-Bukhari 1135
In-book reference : Book 19, Hadith 16
USC-MSA web (English) reference : Vol. 2, Book 21, Hadith 236
  (deprecated numbering scheme)