"If the Messenger of Allah ﷺ was setting out on a journey before the sun passed its zenith, he would delay Zuhr until the time of 'Asr, then he would stop and combine the prayer. If the sun passed its zenith before he set out, he would pray Zuhr and then set off.  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا ارْتَحَلَ قَبْلَ أَنْ تَزِيغَ الشَّمْسُ أَخَّرَ الظُّهْرَ إِلَى وَقْتِ الْعَصْرِ ثُمَّ نَزَلَ فَجَمَعَ بَيْنَهُمَا فَإِنْ زَاغَتِ الشَّمْسُ قَبْلَ أَنْ يَرْتَحِلَ صَلَّى الظُّهْرَ ثُمَّ رَكِبَ  

It was narrated from Abu At-Tufail 'Amir bin Wathilah that Mu'adh bin Jabal told him that they went out with the Messenger of Allah ﷺ in the year of Tabuk, and the Messenger of Allah ﷺ was joining Zuhr and 'Asr, and Maghrib and 'Isha'. He delayed the prayer one day then he went out and prayed Zuhr and 'Asr together, then he went in and came out again and prayed Maghrib and 'Isha'.  

أَخْبَرَهُ أَنَّهُمْ خَرَجُوا مَعَ رَسُولِ اللَّهِ ﷺ عَامَ تَبُوكَ فَكَانَ رَسُولُ اللَّهِ ﷺ يَجْمَعُ بَيْنَ الظُّهْرِ وَالْعَصْرِ وَالْمَغْرِبِ وَالْعِشَاءِ فَأَخَّرَ الصَّلاَةَ يَوْمًا ثُمَّ خَرَجَ فَصَلَّى الظُّهْرَ وَالْعَصْرَ جَمِيعًا ثُمَّ دَخَلَ ثُمَّ خَرَجَ فَصَلَّى الْمَغْرِبَ وَالْعِشَاءَ