Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 200
Narrated Anas:
The Prophet offered a four-Rak'at Zuhr prayer at Medina and then offered a two Rak'at 'Asr prayer at Dhul-Hulaifa and I heard the companions of the Prophet reciting Talbiya aloud (for Hajj and 'Umra) altogether.