Sahih al-Bukhari, Volume 1, Book 10, Hadith 554 (USC-MSA) ⓘ
Narrated Abu Huraira: Allah's Messenger said, "Whoever could get one rak`a of a prayer, (in its proper time) he has got the prayer."
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، قَالَ أَخْبَرَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ أَدْرَكَ رَكْعَةً مِنَ الصَّلاَةِ فَقَدْ أَدْرَكَ الصَّلاَةَ " .
also referenced under: Book 9, Hadith 56 (In-Book) & Hadith 580 (DarusSalam)