أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، . أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ أَدْرَكَ مِنَ الصَّلاَةِ رَكْعَةً فَقَدْ أَدْرَكَ الصَّلاَةَ " .
It was narrated from Abu Hurairah that the Messenger of Allah (PBUH) said: "Whoever catches up with a Rak'ah of the prayer, then he has caught up with the prayer." Translation Not Available
Book Ref: Sunan An Nisai Book 6 Hadith 558
Web Ref: Sunan An Nisai Vol 1 Book 6 Hadith 554