Whenever the Prophet ﷺ started the journey before noon, he used to delay the Zuhr prayer till the time for the ʿAsr prayer and then he would dismount and pray them together; and whenever the sun declined before he started the journey he used to offer the Zuhr prayer and then ride (for the journey).
كَانَ النَّبِيُّ ﷺ إِذَا ارْتَحَلَ قَبْلَ أَنْ تَزِيغَ الشَّمْسُ أَخَّرَ الظُّهْرَ إِلَى وَقْتِ الْعَصْرِ ثُمَّ يَجْمَعُ بَيْنَهُمَا وَإِذَا زَاغَتْ صَلَّى الظُّهْرَ ثُمَّ رَكِبَ