Abu Dawud Book 2, Hadith Number 1241.
Chapter : A seventh view that imam should lead each section in one rakah severellay and they should not pray the second rakah by themselves.
Narated By Hudhayfah : Tha’labah ibn Zahdam said: We accompanied Sa’d ibn al-‘As at Tabaristan. He stood and said: Which of you prayed along with the Apostle of Allah (PBUH) in time of danger? Hudhayfah said: I then he led one section in one rak’ah and the other section in one rak’ah. They did not pray the second rak’ah by themselves.