Sahih Muslim Book 6, Hadith 56
When the Messenger of Allah (ﷺ) set out on a journey before the sun declined (from the meridian), he delayed the noon prayer till the afternoon prayer, and then dismounted (his ride) and combined them (noon and afternoon prayers), but if the sun had declined before his setting out on a journey, he observed the noon prayer and then mounted (the ride).
I saw the Messenger of Allah (ﷺ) delaying the sunset prayer till he would combine it with the 'Isha' when he hastened to set out on a journey.
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.