Hadees Related to Evil (Burai)

Abu Sa'id Al Khudri Radiyallahu 'anhu narrates: I heard Rasulullah Sallallahu 'alaihi wasallam saying: Anybody amongst you who sees an evil should change it with his hands; if he is unable to do so, then with his tongue; if he is unable to do this (even), then by his heart and this is the weakest form of Iman. (Sahih Muslim)
 
Note: To change it by his heart means that one should at least consider it a vice in his heart and should supplicate for its change.

Hadees Related to Imaan

Abu Hurairah Radiyallahu 'anhu narrates that Rasulullah Sallallahu 'alaihi wasallam said: Renew your Iman! It was asked: O Rasulallah! How do we renew our Iman? He said: Say frequently La ilaha illallah. (Musnad Ahmad, Tabarani, Targhib)

Hadees related to Imaan

Abu Hurairah R.A narrates that Rasulullah Sallallahu 'alaihi wasallam said: Iman(faith) has more than seventy branches;  the superiormost one is saying of La ilaha illALLAH (There is none worthy of worship except ALLAH); and the inferior most is the removal of an obstacle from the way; and Haya is a branch of Iman.(Sahih-muslim)  

Note: The essence of Haya is that it restrains a man from evil and prevents a man from neglecting the obligations that he owes to others.(Riyad-us-Salihin)