The Book of the Times (of Prayer)
6/46. Chapter:
Situations During Which It Is Permissible To Combine Two Prayers
Sunan an-Nasai
أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ، قَالَ أَنْبَأَنَا سُفْيَانُ، قَالَ سَمِعْتُ الزُّهْرِيَّ، قَالَ أَخْبَرَنِي سَالِمٌ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ النَّبِيَّ صلى الله عليه وسلم إِذَا جَدَّ بِهِ السَّيْرُ جَمَعَ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ .
Sufyan said: "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'."
Reference : Sunan an-Nasa'i 600In-book reference : Book 6, Hadith 107English translation : Vol. 1, Book 6, Hadith 601