מדרש על תהילים 18:28

He likewise tests the poor. If they do not complain in this world, they will receive their reward in the world-to-come, as is said: For thou dost save the afflicted people (Ps. 18:28). Job suffered in this world and was repaid twofold, as it is said: And the Lord gave Job twice as much as he had before (Job 42:10).