The Messenger of Allah said, 'He who learns his lessons in this world lives in it like a man asleep: he sees it but does not touch it. Abhorrence is increased in his heart and in his self by the behaviour of those who are deceived by this world, which can only bring the reckoning and punishment. He exchanges that world for what will bring him near to Allah's pleasure and pardon. He washes himself free of those things to which the world invites him, and of its worldly adornments, with the water of the world's extinction.
Taking heed brings three things to the person who does so: knowledge of what he does, acting by what he knows, and knowledge of what he does not know. The root of taking heed lies in one's fear of its outcome, when he sees that he has fully realized abstinence at the beginning. Taking heed is only successful for those who have purity and insight.
فَاعْتَبِرُوا يَا أُولِي الْأَبْصَارِ
Take a lesson, O you who have eyes! (59:2)
فَإِنَّهَا لَا تَعْمَى الْأَبْصَارُ وَلَكِن تَعْمَى الْقُلُوبُ الَّتِي فِي الصُّدُورِ
For surely it is not the eyes that are blind, but blind are the hearts which are in the breasts. (22:46)
When Allah opens the eye of someone's heart and insight by means of consideration, then He has given him a high station and an immense fortune.