Surah 18:94
"They said, “Dhū-l-Qarnayn! Surely Yajūj and Majūj are fomenting corruption on the earth. Shall we pay tribute to you on (the condition) that you construct a barrier between us and them?”"
Yajūj and Majūj seem to echo the ruler “Gog” and the people of “Magog” in Ezekiel 38–39 (also Q 21.96). Here they are associated with Alexander, as they are also in postbiblical Christian writings such as the Syriac “Legend of Alexander.” In Muslim tradition Yajūj and Majūj have become part of the end time events.
- from The Quran with Christian Commentary: A Guide to Understanding the Scripture of Islam