The Book of Prayer
Bulugh al-Maram #190
كتاب الصلاة
وَعَنْ أَبِي هُرَيْرَةَ - رضى الله عنه - أَنَّ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -قَالَ: «مَنْ أَدْرَكَ مِنْ اَلصُّبْحِ رَكْعَةً قَبْلِ أَنْ تَطْلُعَ اَلشَّمْسُ فَقَدْ أَدْرَكَ اَلصُّبْحَ, وَمَنْ أَدْرَكَ رَكْعَةً مِنْ اَلْعَصْرِ قَبْلَ أَنْ تَغْرُبَ اَلشَّمْسُ فَقَدْ أَدْرَكَ اَلْعَصْرَ» مُتَّفَقٌ عَلَيْهِ
Narrated Abu Hurairah (RA):
The Prophet (ﷺ) said: “He who prays a Rak'a of the Fajr prayer before the sun rises, has offered the dawn prayer in its time, and he who prays a Rak'a of the 'Asr prayer before the sun sets has offered the afternoon prayer.”
وَعَنْ أَبِي هُرَيْرَةَ - رضى الله عنه - أَنَّ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -قَالَ: "مَنْ أَدْرَكَ مِنْ اَلصُّبْحِ رَكْعَةً قَبْلِ أَنْ تَطْلُعَ اَلشَّمْسُ فَقَدْ أَدْرَكَ اَلصُّبْحَ, وَمَنْ أَدْرَكَ رَكْعَةً مِنْ اَلْعَصْرِ قَبْلَ أَنْ تَغْرُبَ اَلشَّمْسُ فَقَدْ أَدْرَكَ اَلْعَصْرَ" مُتَّفَقٌ عَلَيْهِ
The Prophet (ﷺ) said: "He who prays a Rak'a of the Fajr prayer before the sun rises, has offered the dawn prayer in its time, and he who prays a Rak'a of the 'Asr prayer before the sun sets has offered the afternoon prayer."
— Bulugh al-Maram, Hadith 190