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.
Hadith Referenceصحيح البخاري / كتاب الجهاد والسير / 2951
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة