Verse 18:83

وَيَسْـَٔلُونَكَ عَن ذِى ٱلْقَرْنَيْنِ ۖ قُلْ سَأَتْلُوا۟ عَلَيْكُم مِّنْهُ ذِكْرًا

“And they ask you about Dhū al-Qarnayn. Say: I will recite to you a mention of him.”