It is narrated from Hazrat Zain ul Abideen that when the Messenger of Allah, peace and blessings be upon him, wished to travel during the day, he would combine Zuhr and Asr prayers, and when he wished to travel at night, he would combine Maghrib and Isha prayers.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب قصر الصلاة في السفر / 332