In the Omphaloskepsis edition of the Persian poet Saadi's Gulistan (Rose Garden), based on the translation of Edward Rehatsek, Saadi mentions this tradition:
The tradition is that whenever a sinful and distressed worshipper stretches forth the hand of repentance with hopes of acceptance to the court of heaven, God the most high does not notice him, whereon he continues to implore mercy with supplications and tears and God the most holy says: O my angels, verily I am ashamed of my servant and he has no other lord besides myself. Accordingly I have fully pardoned him.
Is this based on an authentic Islamic tradition, such as a Hadith Qudsi? I can't find one relating this tradition.