Allah the Almighty declared: And (remember) Ishmael and Idris (Enoch) and Dhul-Kifl, all were from among those who observe patience. Surah 21: 85-86

Immediately following Job's story in the Qur'an, Almighty Allah also directed: And remember Our slaves, Abraham, Isaac, and Jacob, (all) owners of strength (in worshiping Us) and (also) of religious understanding. Verily, We did choose them by granting them (a good thing, - i.e. ) the remembrance of the home in the Hereafter and they used to make the people remember it, and also they used to invite the people to obey Allah and to do good deeds for the Hereafter. And they are in Our Sight, verily, of the chosen and the best! And remember Ishmael, Elisha, and Dhul-Kifl, all are among the best. Surah 38: 45-48

It is obvious from his being mentioned and praised in the Glorious Qur'an along with those other prophets that Dhul-Kifl was a prophet.

However, some of the Qur'anic commentators assumed that he was not a prophet but that he was righteous and strictly just.

The Meaning of Dhul-Kifl
Ibn Jarir narrated that he was not a prophet but he was a righteous man. He supported his people to suffice their needs and administered justice among them. That is why he was called Dhul-Kifl .Dhul-Kifl literally means "possessor of. or giving. a double requital or portion". (Source: A. Yusuf All, The Holy Quran: Translation and Commentary, footnote 2743 to murak 2 1:85.)