Sahih Bukhari
Funerals (Al-Janaaiz)
Volume: 002 / Book Number: 023 / Hadith Number: 404
Narrated Abu Huraira:
The Prophet (p.b.u.h) informed his companions about the death of AnNajashi and then he went ahead (to lead the prayer) and the people lined up behind him in rows and he said four Takbir.