مُوَطَّأُ مَالِكٍ
Muwatta Malik 17
The Times of Prayer
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، وَزَيْدَ بْنَ ثَابِتٍ، كَانَا يَقُولاَنِ مَنْ أَدْرَكَ الرَّكْعَةَ فَقَدْ أَدْرَكَ السَّجْدَةَ .
Yahya related to me from Malik that he had heard that Abdullah ibn Umar and Zayd ibn Thabit used to say, "Whoever catches the raka`ah has caught the sajda."
Arabic/English book reference: Book 1, Hadith 17