(30) باب مَنْ أَدْرَكَ رَكْعَةً مِنَ الصَّلاَةِ فَقَدْ أَدْرَكَ تِلْكَ الصَّلاَةَ
Abu Huraira reported the Messenger of Allah (ﷺ) as saying:
He who finds one rak'ah of the prayer with the Imam, he in fact finds the prayer. (ID)
Reference (ID): Sahih Muslim 607 b (ID)
In-book reference (ID): Book 5, Hadith 206 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1261 (ID)