It was narrated that Ibn 'Umar said:
"If the Messenger of Allah (ﷺ) was in a hurry to travel, or some emergency arose, he would combine Maghrib and 'Isha'." (FR)
English reference (FR): Vol. 1, Book 6, Hadith 600 (FR)
Arabic reference (FR): Book 6, Hadith 606 (FR)