Ibn 'Abbas reported that the Messenger of Allah (ﷺ) combined the prayers as he set on a journey in the expedition to Tabuk. He combined the noon prayer with the afternoon prayer and the sunset prayer with the 'Isha' prayer. Sa'id (one of the rawis) said to Ibn 'Abbas:
What prompted him to do this? He said: He wanted that his Ummah should not be put to (unnecessary) hardship.
‘Abdullāh ibn ‘Umar (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) combined the Maghrib and the ‘Ishā' prayers (at Muzdalifah) with one Iqāmah. He did not offer any voluntary prayers in between or after either of them.
جَمَعَ النَّبِيُّ صلى الله عليه وسلم بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ، كُلُّ وَاحِدَةٍ مِنْهُمَا بِإِقَامَةٍ، وَلَمْ يُسَبِّحْ بَيْنَهُمَا وَلاَ عَلَى إِثْرِ كُلِّ وَاحِدَةٍ مِنْهُمَا.