Sahih Muslim Book 6, Hadith 58
Anas reported that when the Messenger of Allah (ﷺ) had to set out on a journey hurriedly, he delayed the noon prayer to the earlier time for the afternoon prayer, and then he would combine them, and he would delay the sunset prayer to the time when the twilight would disappear and then combine it with the 'Isha' prayer.
When the Messenger of Allah (ﷺ) intended to combine two prayers on a journey, he delayed the noon prayer till came the early time of the afternoon prayer, and then combined the two.
The Messenger of Allah (ﷺ) observed the noon and afternoon prayers together, and the sunset and Isha' prayers together without being in a state of fear or in a state of journey.