Sahih Bukhari Volume 5, Book 57, Hadith Number 102.
Narated By Anas : The Prophet had informed the people about the death of Zaid, Ja’far and Ibn Rawaha before the news of their death reached them. He said with his eyes flowing with tears, “Zaid took the flag and was martyred; then Ja’far took the flag and was martyred, and then Ibn Rawaha took the flag and was martyred. Finally the flag was taken by one of Allah’s Swords (i.e. Khalid bin Al-Walid) and Allah gave them (i.e. the Muslims) victory.”