Sahih Al Bukhari Hadith Number 1684

Narrated `Amr bin Maimun: I saw `Umar, offering the Fajr (morning) prayer at Jam’; then he got up and said, “The pagans did not use to depart (from Jam’) til (peace be upon him) contradicted them and departed from Jam’ before sunrise.”

25  Hajj (Pilgrimage)
Hadith number 1684
Volume no 2
Chapter: 100 (When to depart from Jam’ (i.e., Al-Muzdalifa)