Commander of the Faithful Imām Ḥasan Mujtabā ʿalaihi as-salām was the elder grandson of the Prophet ṣall-Allāhu ʿalaihi wa-sallam from his youngest daughter Sayyida Fāṭima ʿalayhā as-salām, and son of Imām ʿAlī Murtaḍā ʿalayhi as-salām.
He was born on 15 Ramaḍān in the year 3 after Hijrah. On the seventh day of his birth, the Prophet slaughtered two rams and gave away his hair-weight of silver as charity. He was named Ḥasan by his venerated grandfather, and his titles include Abū-Muḥammad, Sayyid and Zakī among others.
He is the second Imām in the Golden Chain of the twelve Imāms of Ahl al-Bayt, first being his father. He is among the five noble Ahl al-Kisāʾ (people of the cloak). He is the fifth in the righteous caliphs of Islam. After his abdication, the caliphate turned into monarchy. This was predicted by the Prophet ṣall-Allāhu ʿalaihi wa-sallam, who said: “Caliphate in my Ummah will be for thirty years, after which, there will be monarchy” (Tirmidhī). This duration was to end in Rabīʿ al-Awwal 41 AH whereas Imām ʿAlī was martyred in Ramadān 40 AH, after whom Imām Ḥasan remained caliph for about six months. He abdicated the caliphate in favour of Amīr Muʿāwiya raḍiy-Allāhu ʿanhu, who ruled in the style of kings [Ḥujjat-Allāh al-Bāligha].
According to sound narrations, he had high resemblance with his noble grandfather from head to chest. The companion Anas ibn Mālik raḍiy-Allāhu ʿanhu said:
“None of them resembled the Messenger of Allāh more than Ḥasan ibn ʿAlī.” [Tirmidhī]