Anas said, "The Prophet ﷺ used to perform ablution for every prayer." I asked Anas, "What did you used to do?' Anas replied, "We used to pray with the same ablution until we break it with Hadath."  

كَانَ النَّبِيُّ ﷺ يَتَوَضَّأُ عِنْدَ كُلِّ صَلاَةٍ قُلْتُ كَيْفَ كُنْتُمْ تَصْنَعُونَ قَالَ يُجْزِئُ أَحَدَنَا الْوُضُوءُ مَا لَمْ يُحْدِثْ  

In the year of the conquest of Khaibar I went with Messenger of Allah ﷺ till we reached As-Sahba' where Messenger of Allah ﷺ led the ʿAsr prayer and asked for the food. Nothing but saweeq was brought and we ate it and drank (water). The Prophet ﷺ got up for the (Maghrib) Prayer, rinsed his mouth with water and then led the prayer without repeating the ablution.  

خَرَجْنَا مَعَ رَسُولِ اللَّهِ ﷺ عَامَ خَيْبَرَ حَتَّى إِذَا كُنَّا بِالصَّهْبَاءِ صَلَّى لَنَا رَسُولُ اللَّهِ ﷺ الْعَصْرَ فَلَمَّا صَلَّى دَعَا بِالأَطْعِمَةِ فَلَمْ يُؤْتَ إِلاَّ بِالسَّوِيقِ فَأَكَلْنَا وَشَرِبْنَا ثُمَّ قَامَ النَّبِيُّ ﷺ إِلَى الْمَغْرِبِ فَمَضْمَضَ ثُمَّ صَلَّى لَنَا الْمَغْرِبَ وَلَمْ يَتَوَضَّأْ