One of his supplications
Nahj al-Balāgha|Volume 1|Book 1|Chapter 78
اللَّهُمَّ اغْفِرْ لِي مَا وَأَيْتُ مِنْ نَفْسِي، وَلَمْ تَجِدْ لَهُ وَفَاءً عِنْدي.
My Allah forgive me what I had promised to myself but Thou didst not find its fulfilment with me.