Sahih al-Bukhari — Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) — Hadith No: 4711
Translation
Narrated `Abdullah:During the Pre-Islamic period of ignorance if any tribe became great in number, we used to say, "Amira the children of so-and-so." Narrated Al-Humaidi: Sufyan narrated to us something and used the word 'Amira