“One who speaks the truth.” It occurs in the Qur’an for Idris (generally identified with Enoch, who is described as a man, of eminent truthfulness. professor Palmer translates the word “confessor” (See Surah xix. 57.)
As-Siddiq is a title said to have been given to the first Khalifah Abu Bakr by Muhammad himself.
Based on Hughes, Dictionary of Islam