the Prophet said: "Whoever catches a Rak'ah of Subh before the sun has risen, then he has caught Subh. Whoever catches a Rak'ah of Asr before the sun has set, then he has caught Asr."
Jami` at-Tirmidhi Book 2, Hadith 38
← Previous Hadith the Prophet said: "Between every two calls (to prayer) there is a Salat for whoever wills."

Jami` at-Tirmidhi Book 2, Hadith 37 Next Hadith → "Allah's Messenger combined the Zuhr and Asr (prayers), and the Maghrib and Isha (prayers) in Al-Madinah, without being in a state of fear, nor due to rain."

Jami` at-Tirmidhi Book 2, Hadith 39