SHAFAQNA (Shia International News Association) – Abu Othman narrated: I was sitting with Salmaan Farsi (RA) under a tree, he took a dried out branch and shook it till all the leaves fell off, then he looked at me and said: Don’t you ask why I did that? I asked: Why did you do that? He replied: Once when I was sitting under a tree with the Prophet of Islam (PBUH), he took a dried out branch and shook it till all its leaves dropped, then he said: Salmaan, why didn’t you ask me why I did that? I asked: What was the purpose of that act? The Prophet (PBUH) replied: When a Muslim carries out the proper ablution (Wudhu) and then performs Salaat (the 5 times daily obligatory prayers), his/her sins will fall off like the leaves of this dried branch .
 Beharul Anwaar, Vol. 82, Page 319.