"The Messenger of Allah used to perform ablution for every prayer, and we used to perform all of the prayers with one ablution."  

كَانَ رَسُولُ اللَّهِ ﷺ يَتَوَضَّأُ لِكُلِّ صَلاَةٍ وَكُنَّا نَحْنُ نُصَلِّي الصَّلَوَاتِ كُلَّهَا بِوُضُوءٍ وَاحِدٍ  

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  

"I saw Jabir bin 'Abdullah performing every prayer with one ablution, and I said: 'What is this?' He said: 'I saw the Messenger of Allah doing this, and I am doing as the Messenger of Allah did.'"  

رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَصْنَعُ هَذَا فَأَنَا أَصْنَعُ كَمَا صَنَعَ رَسُولُ اللَّهِ ﷺ