Holy Qur’an 18:87

Until, when he reached the setting of the sun, he found it setting in a pool of murky water, and near it he found a people. We said, ‘O Dhu’l Qarnain, either punish them, or treat them with kindness.’

Translation: Maulawi Sher Ali (Ahmadiyya Muslim Jamaat)

Surah 18: Al-Kahf