Surah Al-Kahf Verse 98

2444 After all the effort which Dhu al Qarnayn has made for their protection, he claims no credit for himself beyond that of discharging his duty as a ruler. He turns their attention to Allah, Who has provided the ways and means by which they can be helped and protected. But all such human precautions are apt to become futile. The time must come when they will crumble into dust. Allah has said so in His Revelation; and His word is true. And so the spiritual lesson from the third episode is: Take human precautions and do all in your power to protect yourselves from evil. But no protection is complete unless you seek the help and grace of Allah. The best of our precautions must crumble to dust when the appointed Day arrives.