Flag-Bearer During the Battle of Uhud

When Ibn Qami‘ah martyred Hazrat Mus‘ab (ra) bin Umair during the Battle of Uhud, he thought that he had martyred the Holy Prophet (sa). Hence, he returned to the Quraish and said that he had killed Muhammad (sa). When Hazrat Mus‘ab (ra) was martyred, the Holy Prophet (sa) handed the flag to Hazrat Ali (ra). Thus, Hazrat Ali (ra) and the Muslims continued in the battle.

(Ibn Hisham, Al-Sirah al-Nabawiyyah, Ghazwat Uhud, Maqtal Mus‘ab bin Umair [Beirut, Lebanon: Dar al-Kutub al-Ilmiyyah, 2001], 529)