Sunan an-Nasa'i 556
سنن النسائي#556Sahihأَخْبَرَنِي شُعَيْبُ بْنُ شُعَيْبِ بْنِ إِسْحَاقَ، قَالَ حَدَّثَنَا أَبُو الْمُغِيرَةِ، قَالَ حَدَّثَنَا الأَوْزَاعِيُّ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ أَدْرَكَ مِنَ الصَّلاَةِ رَكْعَةً فَقَدْ أَدْرَكَهَا " .
It was narrated that Abu Hurairah said:"The Messenger of Allah (ﷺ) said: 'Whoever catches up with a Rak'ah of the prayer has caught up with it
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 6:63