Abu Dawud Book 2, Hadith Number 579.
Chapter : Not known.
Narated By Abdullah ibn Umar : Sulayman, the freed slave of Maymunah, said: I came to Ibn Umar at Bilat (a place in Medina) while the people were praying. I said: Do you not pray along with them? He said: I heard the Apostle of Allah (PBUH) say: Do not say a prayer twice in a day.