Al-Kahf 18:94

They said, “O Dhul-Qarnayn, Gog and Magog are spreading corruption in the land. Can we give you some payment in return for you to construct a barrier between us and them?”

They said, "O Dhul-Qarnayn, indeed Gog and Magog[798] are [great] corrupters in the land. So may we assign for you an expenditure that you might make between us and them a barrier?"

[798] Savage tribes who had ravaged large parts of central Asia, committing every kind of atrocity.

94. They said: "O Dhul-Qarnain! Verily Ya’jûj and Ma’jûj (Gog and Magog)[7] are doing great mischief in the land. Shall we then pay you a tribute in order that you might erect a barrier between us and them?"

[7] (V.18:94) Ya’jûj and Ma’jûj [Gog and Magog (people)]: To know about them in detail - please see Tafsir Al-Qurtubi, Vol. II, Pages 55-58.
Narrated Zainab bint Jahsh that one day Allâh’s Messenger صلى الله عليه وسلم entered upon her in a state of fear and said, " Lâ ilâha illallâh (none has the right to be worshipped but Allâh)! Woe to the Arabs from the great evil that has approached (them). Today a hole has been opened in the dam of Ya’jûj and Ma’jûj (Gog and Magog) like this." The Prophet صلى الله عليه وسلم made a circle with his index finger and thumb. Zainab bint Jahsh added: I said, "O Allâh’s Messenger!, Shall we be destroyed though there will be righteous people among us?" The Prophet صلى الله عليه وسلم said: "Yes if Al-Khabath * (evil persons) increased." (Sahih Al-Bukhari, Vol.9, Hadith No.249).
*The word Al-Khabath is interpreted as illegal sexual intercourse and illegitimate children and every kind of evil deed. (See Fath Al-Bari, Vol. 16, Page 225).

They said: O Dhu'l-Qarneyn! Lo! Gog and Magog are spoiling the land. So may we pay thee tribute on condition that thou set a barrier between us and them?