Original sentence: Sunni Muslims use it to refer to the first four Caliphs, the Four Rightly Guided Caliphs.The title is also used by Shia Muslims to refer to their first Imam, Ali ibn Abi Talib, since he was also the Caliph
Edited sentence: The first Caliph to be called Amir al-Mu'minin were Umar ibn al-Khattāb, the second of the Four Rightly Guided Caliphs, Uthman ibn Affan and Ali ibn Abi Talib also were called by the same title.The title is also used by Shia Muslims to refer to their first Imam, Ali ibn Abi Talib