The Prophet used to perform ablution for every prayer, but on the day of the conquest of Makkah, he performed all of the prayers with one ablution.
أَنَّ النَّبِيَّ ﷺ كَانَ يَتَوَضَّأُ لِكُلِّ صَلاَةٍ فَلَمَّا كَانَ يَوْمُ فَتْحِ مَكَّةَ صَلَّى الصَّلَوَاتِ كُلَّهَا بِوُضُوءٍ وَاحِدٍ