One day, the Prophet Moses (peace be upon him) asked Allah Almighty to show him his worst servant, the Prophet Moses (peace be upon him) was asked to go to the entrance of the town the next morning and the first person who leaves the city is the worst servant of mine.
Prophet Moses went to the entrance of the city the next morning and saw a man with his son are the first ones who left the city.
The Prophet Moses said: this poor man doesn't know that he is the worst creature of Allah Almighty, while returning, he thanked Allah Almighty for answering to his will and then asked Allah Almighty if he could see the best servant of him.
The prophet Moses was asked to go to the entrance of the city late in the evening and the last person who enters the town is my best servant.
When the prophet Moses went to the entrance of the town he saw the same man with his son who entered the town after all. The prophet Moses asked Allah: how is it possible that your best and worst servant is one person?
The Prophet Moses heard: O Moses! This servant of mine was the worst one when he left the town in the morning, but when his son saw the huge and massive mountains around the city asked his father: O father! what is bigger than these mountains?
The father said: the skies.
The son asked: what is bigger than the skies?
While looking at his son, the tears flowed out of his eyes and said: O my son! The sins of your father are even bigger than the skies.
The son asked: what is bigger than your sins?
The father, who could no longer help crying, suddenly burst into tears and said: O my dear son! The kindness and forgiveness of Allah Almighty are bigger than anything that exist in the whole universe.
source : erfan.ir