مُوَطَّأُ مَالِكٍ
Muwatta Malik 18
The Times of Prayer
وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ أَبَا هُرَيْرَةَ، كَانَ يَقُولُ مَنْ أَدْرَكَ الرَّكْعَةَ فَقَدْ أَدْرَكَ السَّجْدَةَ وَمَنْ فَاتَهُ قِرَاءَةُ أُمِّ الْقُرْآنِ فَقَدْ فَاتَهُ خَيْرٌ كَثِيرٌ .
Yahya related to me from Malik that he had heard that Abu Hurayra used to say, "Whoever catches the ruku has caught the sajda and whoever misses the recitation of the umm al-Qur'an has missed much good."
Arabic/English book reference: Book 1, Hadith 18