(9) باب طُولِ الْقِيَامِ فِي صَلاَةِ اللَّيْلِ
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)."
Reference: Sahih al-Bukhari 1135
In-book reference: Book 19, Hadith 16
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 21, Hadith 236