We were sitting with the Prophet (s.a.w.a.) when Ali b. Abi Talib (a.s.) entered.
Ali said, ASSALAAMO ALAIKA, O Messenger of Allah.
The Prophet (s.a.w.a.) replied, WA ALAIK ASSALAAM, O Ameerul Momineen (Commander of the Believers).
Ali responded, O Prophet, you call me Ameerul Momineen while you are still alive?
The Prophet (s.a.w.a.) answered, Yes, while I am alive.
Then the Prophet (s.a.w.a.) continued, O Ali! You passed by Jibraeel and me yesterday and did not say Salaam. So Jibraeel said, Why did Ameerul Momineen (a.s.) not say Salaam to us. I swear to Allah, we
would have been pleased if he had said Salaam to us and we would have responded.
Ali answered, It looked like you and Dehya were in a private meeting so I did not want to interrupt.
The Prophet (s.a.w.a.) said, He was not Dehya, he was Jibraeel. I asked Jibraeel why he called you Ameerul Momineen. Jibraeel told me that in the Battle of Badr, Allah told Jibraeel to come to me (the Prophet) and tell me to order Ameerul Momineen (a.s.) to ride his horse in front of the army lines because the angels love to watch him do that. So Allah named you Ameerul Momineen (a.s.) that day in the heavens.
Then the Prophet (s.a.w.a.) said, O Ali! You are the commander of everyone in the heavens and the commander of everyone on earth. You are the commander of those who have passed away and the commander of those who are yet to come. There is no commander before you and no commander after you. It is forbidden for anyone who has not received this title from Allah to be called by this name.
(Dehya Al-Kalbi was one the companions of the Prophet (s.a.w.a.). He was raised by the Prophet (s.a.w.a.) and he was very
handsome. It was very common for Angel Jibraeel to come down to Prophet in the form of Dehya. The Prophet
had ordered his companions not to approach him when they saw him alone with Dehya).
Ghaayah al-Maraam p 18 Behaar al-Anwaar v 37 p 307 Al-Manaaqeb v 2 p 253