From the Mathnawi

   

     
A certain saintly man used to always perform his salaah with the congregation in the mosque. One day as usual he went to the mosque for salaah. As he reached the door of the mosque, he heard the voice of the Imam saying: "Assalaamu Alaykum Wa Rahmatullah" indicating that the congregational salaah had ended. Realizing that he had missed the congregational salaah, the pious man was filled with so much sorrow that he sighed: "Ah!" Such a sigh came right from the depths of his heart. "The saintly man missed the congregation and 'Ah!' was uttered in sorrow and in his 'Ah' the blood of his heart could be smelt".

     Inside the mosque, there was another saintly person with a
spiritual insight. When he came out of the mosque, he saw a celestial light, which went right up to the Throne of Allah Ta’ala.  He discovered that the light was the sigh of the person who had missed the congregational prayer. He said to the pious one: "Hazrat give me that 'Ah!' and in exchange accept my Salaah which was performed with the congregation.”

The saint did not, at the time, understand the real value of his "Ah!" and exchanged it for the Salaah with congregation. That night the other saint saw a dream wherein a voice from heaven said to him: "O man, you have purchased and acquired the water of life, the water of health and have made a very good exchange in getting that 'Ah!' because that sigh was uttered in the fullest sincerity".

"That night a messenger from on high brought the message that through that transaction he had acquired the water of life and of health. And said: Through this transaction that you have made,
Allah Ta’ala has accepted the Salaah of all mankind of the present time."

From this we can learn the following things:
One should not look down upon anyone. Sometimes even a great sinner repents so sincerely, with such a presence of heart and in such a heart-rending manner that his repentance becomes superior to all his other deeds, with the result that we do not know from where to where he reaches.
Maulana says:
"Taubah (repentance) is a strange means of conveyance. It causes one to reach speedily from humbleness and lowliness Up to acceptance and great heights". From this, we also learn that when there are shortcomings and faults in our deeds, we should have sorrow, grief and remorse and we should cry before Allah Ta’ala seeking forgiveness and pardon. In the story all that was included in one" Ah!”