Sahih al-Bukhari 18:32
Narrated Anas bin Malik:
Whenever the Prophet (ﷺ) started on a journey before noon, he used to delay the Zuhr prayers till the time for the 'Asr prayer and then he would dismount and offer them together; and whenever the sun declined before he started on a journey he used to offer the Zuhr prayers and then ride (for journey).
Reference
Sahih al-Bukhari 18:32
In-book reference
Book 18, Hadith 32
Arabic Text
حَدَّثَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا الْمُفَضَّلُ بْنُ فَضَالَةَ، عَنْ عُقَيْلٍ، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم 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.