Learn this from the holy Gospels, that prayer remits sins. Therefore, what are they saying? The Kingdom of the Heavens resembles a certain man who closed his door and reclined to sleep along with his children. In the evening, someone came wanting to receive loaves of bread from him and knocked on his door, saying, “Open up for me, because I have need of loaves of bread.” And he answered, “Now I cannot give you any, because we and our children? have lain down to sleep.” However, he persisted in knocking on the door. Again He said to him, “I cannot offer you any, because we and the children have lain down to sleep.” Although he heard these things, he persisted in knocking and did not withdraw until the master of the house said about him, “Arise, give him whatever he wants and let him depart.” There-fore, the Gospel teaches you to pray unceasingly. Even if you do not gain anything, stand fast; perhaps you may gain something in the future.
St. John Chrysostom
Fathers in Iconography 