AL-MASUIDU ‘L-AQSA المسجد الاقصى
Lit. “The Most Distant Mosque.” The temple at Jerusalem erected by Solomon, called also al-Baitu ‘l-Muqaddas, or “the Holy House.” Known also in Muslim literature as as-Sakhrah, “the Rock.” from which it is believed Muhammad ascended to heaven on the occasion of his celestial journey. (See Qur’an, Surah xvii.)
Jalalu ‘d-din as-Suyuty has devoted a whole volume to the consideration of the superabundant merits existing in the Masjidu ‘l-Aqsa, which work has been translated into English by the Rev. James Reynolds (Oriental Translation Fund, 1836). He says ft is called al-Aqsa, because it is the most distant mosque to which pilgrimage is directed. [JERUSALEM, AS-SAKHRAH.]

Based on Hughes, Dictionary of Islam