"Whoever catches up with a Rak'ah of Fajr before the sun rises, then he has caught up with it; and whoever catches up with a Rak'ah of 'Asr before the sun sets, then he has caught up with it."
Sunan an-Nasa'i Book 6, Hadith 58
← Previous Hadith "Whoever catches up with a prostration of Subh before the sun rises, then he has caught up with it; and whoever catches up with a prostration of 'Asr before the sun sets, then he has caught up with it."

Sunan an-Nasa'i Book 6, Hadith 57 Next Hadith → "The Messenger of Allah (ﷺ) used to pray Zuhr when the sun passed its zenith, and he would pray 'Asr between these two prayers; and he would pray Maghrib when the sun had set, and he used to pray 'Isha' when the twilight had disappeared," then he said straight after that: "And he would pray Fajr when a man could see clearly."

Sunan an-Nasa'i Book 6, Hadith 59