Must I show you a great sin, from among the greatest sins?" The sahaabah replied, "Yes O Rasoolullah sallallahu alaihe wasallam, do tell us." Rasoolullah sallallahu alaihe wasallam replied, "To ascribe a partner unto Allah. To disobey one's parents. To bare false witness, (or tell a lie). (The narrator is not sure which of the two Sayyidina Rasoolullah sallallahu alaihe wasallam had said). At that time Rasoolullah sallallahu alaihe wasallam was leaning on something. When he mentioned lies, he sat up, and because of its importance began to repeat it many times, till we began hoping that he would stop, and not repeat it so many times".