Prophet (salAllahu alayhi wasallam) said, “Indeed a person with good character would reach the level of the one who constantly fasts in the day and stands at night.” 

 Narrated by Abu Dawud (3798), ibn Hibban (1967), and Al-Hakim (1/60). Al-Albani said that the hadith is sahih (Silsilah as-sahihah: 2/421)