Muwatta Malik, Book 9, Hadith 3 (USC-MSA) ⓘ
3 Yahya related to me from Malik from Nafi that Abdullah ibn Umar said, "The Messenger of Allah, may Allah bless him and grant him peace, used to join maghrib and isha together when it was urgent to travel."
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا عَجِلَ بِهِ السَّيْرُ يَجْمَعُ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ .
also referenced under: Book 9, Hadith 331 (In-Book)