(5) باب جَوَازِ الْجَمْعِ بَيْنَ الصَّلاَتَيْنِ فِي السَّفَرِ
Nafi' reported that when Ibn 'Umar was in a state of hurry on a journey, he combined the sunset and 'Isha' prayers after the twilight had disappeared, and he would say that when the Messenger of Allah (ﷺ) was in a state of hurry on a journey, he combined the sunset and 'Isha' prayers.
Reference: Sahih Muslim 703 b
In-book reference: Book 6, Hadith 53
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1509