The life of man
Ibn al-Qayyim, may Allah have mercy upon him:
“Verily the life of man is in the life of his heart and his soul.
And there is no life in the heart except by knowing its Creator, having love for Him, worshipping Him solely, turning to Him in times of need, and seeking tranquility with His remembrance.
And he who loses this life has lost all good.
Even if he attempts to substitute (this loss) with all that is in the world.
For verily not even all of the world together would be able to replace this life.
And verily for everything that a slave loses there is a substitute, but the one who loses Allah will never find anything to replace Him.”
Related by Ibn al-Qayyim in ad-Da’ wad-Dawa Fasl 49