Tabarani, Al-Mu’jam Al-Kabir, V.2, page 247; Ibn Asaker, Tarikh Madinah-Damishq, V.42, page 75; Ibn-Dimashqi, Jawaher al-Matalib, V. 1, page 182; Kharazmi, Al-Manaqib, page 358.

It is narrated from Anas that the Messenger of Allah (s.a.w.a.) gave to Abu Bakr the declaration of immunity to the polytheists and dispatched him to Mecca. A short while later, he called him back and said, "It is not worthy of anyone to deliver this letter except for the man who is close to me." Then he called Ali and handed him the letter to be taken to Mecca.

Suyuti, Al-Durr al-Manthur, V.3, page 209; Shawkani, Fath al-Kabir, V.2, page 334; Akin to same contents has come down in Kanzl al-Ummal (Muttaqi Hindi, V.2, p.417, 422) and it is narrated from Ibn Abbas as saying, “Ali was the bearer of the flag of the Messenger of Allah (s.a.w.a.) in the battle of Badr and all the battles.”

Ibn-Dimashqi, Jawaher al-Matalib, V. 1, page 189; Also, refer to Ibn Saad, Tabaqat al-Kubra, V.3, page 23.

And it is narrated from Ibn Abbas who said, “In the battle of Uhud, Ali’s hand was injured and the flag fell from his hand. The Messenger of Allah (s.a.w.a.) said: Place the flag in his left hand because he is my flag bearer in both the worlds.”

Tabari, Al-Riaz ul-Nazra, V.3, page 156; Ibn-Dimashqi, Jawaher al-Matalib, V. 1, page 190.