Sin (from Sahih Al- Bukhari)

Narrated Abu Huraira(R): I heard Allah's Messenger(S) saying- "All the sins of my followers will be forgiven except those of the Mujahirun(those who commit a sin openly or disclose their sins to the people). An example of such disclosure is that a person commits a sin at night and though Allah screens it from the public, then he comes in the morning, and says, 'O so-and-so,I did such and such (evil) deed yesterday,' though he spent his night screened by his Lord (none knowing about his sin) and in the morning he removes Allah's screen from himself [8:95-O.D]