Sahih Muslim Book 4, Hadith Number 1917.

Chapter : What is to be recited in the Jumu’a prayer ?.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: When any one amongst you observes prayer after Jumu’a, he should observe four rak’ahs. (In the Hadith transmitted by Jarir the word minkum is not recorded.)