Caliph Al-Hasan ibn ‘Ali is the grandson of which Islamic prophet?
Mujtaba Al-Mujtaba (Arabic: اَلْـمُـجْـتَـبَى‎ ‎ ) is an Arabic word which means "The Selected One" or "The Chosen One among many." It is a title of the Islamic "Nabi" (Arabic: نَـبِي‎ ‎ , Prophet) Muhammad, and his grandson, the Caliph Al-Hasan ibn ‘Ali.
Al-Wathiq Abū Jaʿfar Hārūn ibn Muḥammad (Arabic: أبو جعفر هارون بن محمد المعتصم‎ ‎ ; 18 April 812 – 10 August 847), better known by his regnal name al-Wāthiq Bi’llāh (الواثق بالله , "He who trusts in God"), was an Abbasid caliph who reigned from 842 until 847 AD (227–232 AH in the Islamic calendar).