"Whoever catches up with a Rak'ah of the Subh prayer before the sun rises, then he has caught up with Subh, and whoever catches up with a Rak'ah of 'Asr prayer before the sun sets, then he has caught up with 'Asr."
Sunan an-Nasa'i Book 6, Hadith 24
← Previous Hadith "If any one of you catches the first prostration of 'Asr prayer before the sun sets, let him complete his prayer, and if he catches up with the first prostration of Fajr prayer before the sub rises, let him complete his prayer."

Sunan an-Nasa'i Book 6, Hadith 23 Next Hadith → 'Are you not going to pray?' He said: 'The Messenger of Allah (ﷺ) said: 'There is no prayer after 'Asr until the sun has set, nor after Subh until the sun has risen.'"

Sunan an-Nasa'i Book 6, Hadith 25