Sahih Muslim Book 4, Hadith Number 1837.

Chapter : Prayer in time of danger.

Abu Huraira reported: Umar b. Khattab was delivering a sermon to the people on Friday when ‘Uthman b. ‘Affan came there. ‘Umar hinting to him said: What would become of those persons who come after the call to prayer? Upon this ‘Uthman said: Commander of the faithful, I did no more than this that after listening to the call, I performed ablution and came (to the mosque). ‘Umar said: Just ablution ! Did you not bear the Messenger of Allah (my peace be upon him) say this: When any one of you comes for Jumu’a, he should take a bath.