From Abu Hurairah (radiyallaahu 'anhu) who said: We said: O Messenger of Allaah! You jest with us? He said (salallaahu 'alaihi wa'sallam):
Yes except that I do not say except what is true.
So falsehood has no share of this, and lies cannot approach it. So his jesting is with words that are true. Nor does this mean that he is to expend all his time in lightheartedness and jesting. Rather in this and in all matters he follows the footsteps of the Companions, May Allaah be pleased with them all, and their way in this regard was: