Once Imam Ali ibn-E-Abi Talib (A.S) was delivering speech to His Followers in the Mosque of Kufa, suddenly Imam Ali (PBUH) stopped and replied to a greeting (Salam). People asked O commander of faithful no one came here from now then to whom You replied in response to the greeting. Then Imam Ali (PBUH) said some flying birds in the sky have offered their greeting to Me, I’ve replied to them.