From Sahih Bukhari (Hadith 6883):
Narrated `Aisha:The pagans were defeated on the day (of the battle) of Uhud. Satan shouted among the people on the day of Uhud, "O Allah's worshippers! Beware of what is behind you!" So the front file of the army attacked the back files (mistaking them for the enemy) till they killed Al-Yaman. Hudhaifa (bin Al- Yaman) shouted, "My father!" My father! But they killed him. Hudhaifa said, "May Allah forgive you." (The narrator added: Some of the defeated pagans fled till they reached Taif)
Reference: Bukhari 6883