(Imām Bukhārī narrates): Hassan al-Wasiti narrated the hadith to us, he said: Al-Mufaddal bin Fadalah narrated the hadith to us, from Uqail, from Ibn Shihab, from Hazrat Anas bin Malik (Allāh be pleased with him), he narrates that
when the Prophet ﷺ departed before the decline of the sun, he ﷺ would delay the Zuhr prayer until the time of Asr, then combine the two of them, and when the sun declined, he ﷺ would offer the Zuhr prayer, then mount.
حَدَّثَنَا حَسَّانُ الوَاسِطِيُّ ، قَالَ حَدَّثَنَا المُفَضَّلُ بْنُ فَضَالَةَ، عَنْ عُقَيْل، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسِ بْنِ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ
كَانَ النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ إِذَا ارْتَحَلَ قَبْلَ أَنْ تَزِيغَ الشَّمْسُ أَخَّرَ الظُّهْرَ إِلَى وَقتِ العَصْرِ، ثُمَّ يَجْمَعُ بَيْنَهُمَا، وَإِذَا زَاغَتْ صَلَّى الظُّهْرَ ثُمَّ رَكِبَ
Reference: Sahih Al Bukhari 1111