Salim told me, "ʿAbdullah bin ʿUmar said, 'I saw Messenger of Allah ﷺ delaying the Maghrib prayer till he offered it along with the ʿIsha prayer whenever he was in a hurry during the journey.' " Salim said, "Abdullah bin ʿUmar used to do the same whenever he was in a hurry during the journey. After making the call for Iqama, for the Maghrib prayer he used to offer three rakʿat and then perform Taslim. After waiting for a short while, he would pronounce the Iqama for the ʿIsha' prayer and offer two rakʿat and perform Taslim. He never prayed any Nawafil in between the two prayers or after the ʿIsha' prayers till he got up in the middle of the night (for Tahajjud prayer)."  

رَأَيْتُ رَسُولَ اللَّهِ ﷺ إِذَا أَعْجَلَهُ السَّيْرُ فِي السَّفَرِ يُؤَخِّرُ صَلاَةَ الْمَغْرِبِ حَتَّى يَجْمَعَ بَيْنَهَا وَبَيْنَ الْعِشَاءِ قَالَ سَالِمٌ وَكَانَ عَبْدُ اللَّهِ يَفْعَلُهُ إِذَا أَعْجَلَهُ السَّيْرُ وَيُقِيمُ الْمَغْرِبَ فَيُصَلِّيهَا ثَلاَثًا ثُمَّ يُسَلِّمُ ثُمَّ قَلَّمَا يَلْبَثُ حَتَّى يُقِيمَ الْعِشَاءَ فَيُصَلِّيهَا رَكْعَتَيْنِ ثُمَّ يُسَلِّمُ وَلاَ يُسَبِّحُ بَيْنَهَا بِرَكْعَةٍ وَلاَ بَعْدَ الْعِشَاءِ بِسَجْدَةٍ حَتَّى يَقُومَ مِنْ جَوْفِ اللَّيْلِ  

Whenever the Prophet ﷺ started a journey before noon, he used to delay the Zuhr prayer till the time of ʿAsr and then offer them together; and if the sun declined (at noon) he used to offer the Zuhr prayer and then ride (for the journey).  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَجْمَعُ بَيْنَ هَاتَيْنِ الصَّلاَتَيْنِ فِي السَّفَرِ يَعْنِي الْمَغْرِبَ وَالْعِشَاءَ