Imam Al-Ridha: A true believer is he who feels happy when he does a good deed and prays God to forgive him when he commits an evildoing.

الإمام الرضا: الْمُؤْمِنُ الَّذِي إِذَا أَحْسَنَ‏ اسْتَبْشَرَ وَإِذَا أَسَاءَ اسْتَغْفَرَ