Quoting Imam al-Sadiq (a.s), Ishaq ibn `Ammar has reported: I was spreading my father’s bed and waiting for him to come. When he would go to his bed and sleep, then I would go to mine. One night, he was late. I went to the mosque to look for him. While all people had gone home, I found him alone in the mosque in prostration. I heard his lamentation, saying,
سُبْحَانَكَ اللَّهُمَّ رَبِّي حَقّاً حَقّاً. سَجَدْتُ لَكَ يَا رَبِّ تَعَبُّداً وَرِقّاً. أللَّهُمَّ إنَّ عَمَلِي ضَعِيفٌ فَضَاعِفْهُ لِي. أللَّهُمَّ قِنِي عَذَابَكَ يَوْمَ تَبْعَثُ عِبَادَكَ، وَتُبْ عَلَيَّ إنَّكَ أنْتَ التَّوَّابُ الرَّحِيمُ.
Glory be to You, O my Lord, with true glory! I am prostrating myself before You, O my God, worshipping and serving You! O Allah! My deed is weak; (please) double its reward. O Lord! Preserve me from Your punishment when You resurrect Your servants. Accept my repentance for You are the best Accepter of repentance and the most Merciful. ( Al-Kafi: 323/3, H 9. )