Sunan an-Nasa'i, Book 6, Hadith 601 (In-Book) ⓘ

It was narrated from Anas that the Messenger of Allah said: "If the Messenger of Allah wanted to travel quickly, he would delay Zuhr until the time of 'Asr and combine them, and he would delay Maghrib until he combined it with 'Isha' when the twilight had disappeared."

أَخْبَرَنِي عَمْرُو بْنُ سَوَّادِ بْنِ الأَسْوَدِ بْنِ عَمْرٍو، قَالَ أَنْبَأَنَا ابْنُ وَهْبٍ، قَالَ حَدَّثَنَا جَابِرُ بْنُ إِسْمَاعِيلَ، عَنْ عُقَيْلٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسٍ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم أَنَّهُ كَانَ إِذَا عَجِلَ بِهِ السَّيْرُ يُؤَخِّرُ الظُّهْرَ إِلَى وَقْتِ الْعَصْرِ فَيَجْمَعُ بَيْنَهُمَا وَيُؤَخِّرُ الْمَغْرِبَ حَتَّى يَجْمَعَ بَيْنَهَا وَبَيْنَ الْعِشَاءِ حِينَ يَغِيبُ الشَّفَقُ ‏.‏