Prayer (Kitab Al-Salat): Details of Commencing Prayer
Dawud :: Book 3 : Hadith 1123
Narrated Abdullah ibn Umar:
Nafi' said: Ibn Umar used to lengthen his prayer before the Friday prayer and would offer two rak'ahs after it in his house. He used to say that the Apostle of Allah (peace_be_upon_him) would do that.