المعنى الاصطلاحي :

The righteous slave whom Allah, the Almighty, mentioned his story with the Prophet Mūsa (Moses), peace be upon him, in Sūrat al-Kahf.

الشرح المختصر :

"Al-Khadir" is a slave of Allah, the Almighty, whose story has been mentioned along with the Prophet Mūsa (Moses), peace be upon him, in the Noble Qur’an in general. This story has been mentioned with some details in the Prophetic tradition. There are two different opinions regarding why he was named "al-Khadir": 1. Because he sat on a dry barren land and it turned into a green land underneath him. 2. Because wherever he used to sit, everything around him would turn green. Scholars hold different opinions concerning his prophethood, the most famous of which are two opinions: The first opinion is that he was a prophet, and this is the opinion of the majority of scholars, including Al-Qurtubi, Ibn Kathīr, Ibn Hajar, Muhammad al-Amīn ash-Shinqīti, and others. These scholars, however, differ on whether he is a messenger or only a prophet, and most of them hold that he was only a prophet. The second opinion, which is held by some scholars, is that he was a righteous slave of Allah, and not a prophet. The sound opinion regarding his life is that he had passed away. This is the opinion of the competent verified scholars, such as Al-Bukhāri, Imam Ahmad, Ibn al-Jawzi, Ibn Taymiyyah, Ibn Hajar, and others. Some Sufis and others, however, claim that he is still alive.