I asked A'ishah about the voluntary prayers offered by the Messenger of Allah ﷺ. She replied: Before the noon prayer he would pray four rak'ahs in my house, then go out and lead the people in prayer, then return to my house and pray two rak'ahs. He would lead the people in the sunset prayer, then return to my house and pray two rak'ahs. Then he would lead the people in the night prayer, and enter my house and pray two rak'ahs. He would pray nine rak'ahs during the night, including witr (prayer). At night he would pray for a long time standing and for a long time sitting. When he recited the Qur'an while standing, he would bow and prostrate himself from the standing position, and when he recited while sitting, he would bow and prostrate himself from the sitting position, and when dawn came he prayed two rak'ahs, then he would come out and lead the people in the dawn prayer. (Using translation from Abū Dāʾūd 1251)   

صَلَاةِ رَسُولِ اللهِ ﷺ مِنَ التَّطَوُّعِ فَقَالَتْ كَانَ يُصَلِّي قَبْلَ الظُّهْرِ أَرْبَعًا فِي بَيْتِي ثُمَّ يَخْرُجُ فَيُصَلِّي بِالنَّاسِ ثُمَّ يَرْجِعُ إِلَى بَيْتِي فَيُصَلِّي رَكْعَتَيْنِ وَكَانَ يُصَلِّي بِالنَّاسِ الْمَغْرِبَ ثُمَّ يَرْجِعُ إِلَى بَيْتِي فَيُصَلِّي رَكْعَتَيْنِ وَكَانَ يُصَلِّي بِهُمُ الْعِشَاءَ ثُمَّ يَدْخُلُ بَيْتِي فَيُصَلِّي رَكْعَتَيْنِ وَكَانَ يُصَلِّي مِنَ اللَّيْلِ تِسْعَ رَكَعَاتٍ فِيهِنَّ الْوِتْرُ وَكَانَ يُصَلِّي لَيْلًا طَوِيلًا قَائِمًا وَلَيْلًا طَوِيلًا جَالِسًا فَإِذَا قَرَأَ وَهُوَ قَائِمٌ رَكَعَ وَسَجَدَ وَهُوَ قَائِمٌ وَإِذَا قَرَأَ وَهُوَ قَاعِدٌ رَكَعَ وَسَجَدَ وَهُوَ قَاعِدٌ وَكَانَ إِذَا طَلَعَ الْفَجْرُ صَلَّى رَكْعَتَيْنِ ثُمَّ يَخْرُجُ فَيُصَلِّي بِالنَّاسِ صَلَاةَ الْفَجْرِ لَفْظُ حَدِيثِ أَبِي دَاوُدَ وَرَوَاهُ مُسْلِمٌ فِي الصَّحِيحِ عَنْ يَحْيَى بْنِ يَحْيَى  

[Machine] The Messenger of Allah ﷺ used to not leave four (units of prayer) before midday and two (units of prayer) before the dawn prayer. Abu Abdullah Al-Hafiz narrated that Abdullah bin Muhammad Al-Ka'bi informed us that Muhammad bin Ayyub informed us that Musaddad informed us that Yahya narrated from Shu'ba, and he mentioned it in a similar manner except that he said: "The Messenger of Allah ﷺ said before the morning prayer."  

كَانَ رَسُولُ اللهِ ﷺ لَا يَدَعُ أَرْبَعًا قَبْلَ الظُّهْرِ وَرَكْعَتَيْنِ قَبْلَ صَلَاةِ الْفَجْرِ 4478 وَأنبأ أَبُو عَبْدِ اللهِ الْحَافِظُ أنبأ عَبْدُ اللهِ بْنُ مُحَمَّدٍ الْكَعْبِيُّ ثنا مُحَمَّدُ بْنُ أَيُّوبَ ثنا مُسَدَّدٌ ثنا يَحْيَى عَنْ شُعْبَةَ فَذَكَرَهُ بِنَحْوِهِ إِلَّا أَنَّهُ قَالَ إِنَّ رَسُولَ اللهِ ﷺ وَقَالَ قَبْلَ صَلَاةِ الْغَدَاةِ  

[Machine] "Whoever prays twelve voluntary rak'ahs every day, not including the obligatory prayers, Allah will build a house for him in Paradise."  

اللهِ ﷺ مَنْ صَلَّى اثْنَتَيْ عَشْرَةَ رَكْعَةً كُلَّ يَوْمٍ تَطَوُّعًا غَيْرَ فَرِيضَةٍ بَنَى اللهُ لَهُ بَيْتًا فِي الْجَنَّةِ لَفْظُ حَدِيثِ عَبْدِ الرَّحْمَنِ وَفِي حَدِيثِ أَبِي دَاوُدَ الطَّيَالِسِيِّ سَمِعَ عَمْرَو بْنَ أَوْسٍ سَمِعَ عَنْبَسَةَ بْنَ أَبِي سُفْيَانَ يُحَدِّثُ عَنْ أُمِّ حَبِيبَةَ أَنَّ النَّبِيَّ ﷺ قَالَ مَنْ صَلَّى ثِنْتَيْ عَشَرَ رَكْعَةً فِي يَوْمٍ وَلَيْلَةٍ سِوَى الْمَكْتُوبَةِ بَنَى اللهُ لَهُ بَيْتًا فِي الْجَنَّةِ قَالَتْ أُمُّ حَبِيبَةَ ؓ مَا تَرَكْتُهُنَّ بَعْدُ قَالَ عَنْبَسَةُ مَا تَرَكْتُهُنَّ بَعْدُ قَالَ عَمْرٌو مَا تَرَكْتُهُنَّ بَعْدُ قَالَ النُّعْمَانُ وَأَنَا مَا أَكَادُ أَنْ أَدَعَهُنَّ بَعْدُ  

"The Messenger of Allah ﷺ said: 'Whoever prays twelve rak'ahs, Allah (SWT) will build for him a house in paradise: four before Zuhr and two after, two before Asr, two after Maghrib, and two before Subh.'" (Using translation from Nasāʾī 1802)   

عَنْ أُمِّ حَبِيبَةَ زَوْجِ النَّبِيِّ ﷺ قَالَتْ قَالَ رَسُولُ اللهِ ﷺ مَنْ صَلَّى ثِنْتَيْ عَشْرَةَ رَكْعَةً بَنَى اللهُ لَهُ بَيْتًا فِي الْجَنَّةِ أَرْبَعًا قَبْلَ الظُّهْرِ وَاثْنَتَيْنِ بَعْدَهَا وَاثْنَتَيْنِ قَبْلَ الْعَصْرِ وَاثْنَتَيْنِ بَعْدَ الْمَغْرِبِ وَاثْنَتَيْنِ قَبْلَ الصُّبْحِ