"The Messenger of Allah (ﷺ) prayed Zuhr and 'Asr together, and Maghrib and 'Isha' together, when there was no fear and he was not traveling."
Sunan an-Nasa'i Book 6, Hadith 108
← Previous Hadith "I heard Az-Zuhri say: 'Salim told me that his father said: 'I saw the Prophet (ﷺ), if he was in a hurry to travel, joining Maghrib and 'Isha'."

Sunan an-Nasa'i Book 6, Hadith 107 Next Hadith → "Why?" He said: "So that there would not be any hardship on his Ummah."

Sunan an-Nasa'i Book 6, Hadith 109