It was narrated from 'Aishah that the Prophet (ﷺ) said:"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
Hadith No. 551
Sunan an Nasai
Gradings:
Abu Ghuddah:
Sahih
Al-Albani:
Sahih
Zubair Ali Zai:
Sahih Muslim