Imam Ali (AS) said: I am amazed at the arrogant person who until yesterday was a worthless sperm, and tomorrow will be a fetid corpse; and I am amazed at the person who sees the creation of phenomenon and doubts the existence of God, and I am amazed at the person who sees the dead ones and has forgotten the death [1].
[1] Nahjul Balaghah, Wisdom 126.