Musannaf Ibn Abi Shaybah 34084 — Reports on Dhul-Qarnayn

Mujahid said: Only four have been kings of the whole earth, two Muslims and two disbelievers. The Muslims are Sulayman bin Dawud and Dhu al-Qarnayn, and the disbelievers are Bukht Nasr and the one who disputed with Ibrahim (peace be upon him) about his Lord.