مُوَطَّأُ مَالِكٍ
Muwatta Malik 178
Prayer
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ حُمَيْدٍ الطَّوِيلِ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّهُ قَالَ قُمْتُ وَرَاءَ أَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَكُلُّهُمْ كَانَ لاَ يَقْرَأُ {بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ } إِذَا افْتَتَحَ الصَّلاَةَ .
Yahya related to me from Malik from Humayd at-Tawil that Anas ibn Malik said, "I stood behind Abu Bakr and Umar and Uthman and none of them used to recite 'In the name of Allah, the Merciful, the Compassionate' when they began the prayer."
Arabic/English book reference: Book 3, Hadith 31