Fārūq (Arabic: فاروق), meaning the demarcating boundary of right and wrong, is a title of Imam Ali (a) given to him by the Prophet Muhammad (s). According to some historical sources, the Jews gave the title "faruq" to the Second Caliph. Al-Tabari and others quoted Ibn Shahab al-Zuhri as saying that "the first people who gave the title to 'Umar b. al-Khattab (the Second Caliph) were Ahl al-Kitab (the People of the Book), and Muslims followed their practice. We do not have any reports from the Prophet (s) on this."
- Khawārizmī, al-Manāqib, p. 105; Qundūzī, Yanābīʿ al-mawadda, vol. 2, p. 234; Ṭūsī, al-Amālī, p. 148.
- Ibn Kathīr al-Dimashqī, al-Bidāya wa l-nihāya, vol. 7, p. 133; Ṭabarī, Tārīkh al-umam wa l-mulūk, vol. 4, p. 195; vol. 11, p. 504.
- Ibn Kathīr al-Dimashqī, Ismāʿīl b. ʿUmar. Al-Bidāya wa l-nihāya. Beirut: Dār al-Fikr, 1407 AH.
- Khawārazmī, Muwafaq b. Aḥmad al-. Al-Manāqib. Edited by Mālik Maḥmūdī. Qom: Muʾassisat al-Nashr al-Islāmī, 1414 AH.
- Qundūzī, Sulaymān b. Ibrāhīm al-. Yanābīʿ al-mawadda li-dhawī l-qurbā. Edited by Sayyid ʿAlī Jamāl Ashraf al-Ḥusaynī. Qom: Dār al-Uswa, 1416 AH.
- Ṭabarī, Muḥammad b. Jarīr al-. Tārīkh al-umam wa l-mulūk. Edited by Abū l-Faḍl Ibrāhīm. Secound edition. Beirut: Dār al-Turāth, 1387 AH.
- Ṭūsī, Muḥammad b. al-Ḥasan al-. Al-Amālī. Edited by Muʾassisat al-Biʿtha. Qom: Dār al-Thiqāfa, 1414 AH.