Sahih Bukhari | Volume 1 | Hadith Number 540

Narrated by Muhammad bin 'Amr
We asked Jabir bin 'Abdullah about the prayers of the Prophet. He said, "He used to pray Zuhr prayer at mid-day, the 'Asr when the sun was still hot, and the Maghrib after sunset (at its stated time). The 'Isha was offered early if the people gathered, and used to be delayed if their number was less; and the morning prayer was offered when it was still dark."