Sunan an-Nasa'i, Book 6, Hadith 607 (In-Book) ⓘ
Sufyan said: "I heard Az-Zuhri say: 'Salim told me that his father said: 'I saw the Prophet, if he was in a hurry to travel, joining Maghrib and 'Isha'."
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 .
also referenced under: Volume 1, Book 6, Hadith 601 (DarusSalam)