Sahih Bukhari
Sahih Bukhari Volume 001, Book 008, Hadith Number 435.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 08. Prayers (Salat)
Narated By Abu Qatada Al-Aslami : Allah's Apostle said, "If anyone of you enters a mosque, he should pray two Rakat before sitting."