Chapter: Evidence that sleeping while sitting does not invalidate wudu’
Anas reported: (The people) stood up for prayer and the Messenger of Allah ( صلی اللہ علیہ وسلم ) was whispering to a man, and in the narration of 'Abd al-Warith (the words are): The Apostle of Allah ( صلی اللہ علیہ وسلم ) was having a private conversation with a man, and did not start the prayer till the people dozed off.
Authentic