He observed thirteen rak'ahs (in the night prayer). He observed eight rak'ahs and would then observe Witr and then observe two rak'ahs sitting, and when he wanted to bow he stood up and then bowed down, and then observed two rak'ahs in between the Adhan and lqama of the dawn prayer. (Using translation from Muslim 738b)   

عَنْ صَلَاةِ رَسُولِ اللهِ ﷺ؟ فَقَالَتْ كَانَ «يُصَلِّي ثَمَانِ رَكَعَاتٍ ثُمَّ يُوتِرُ ثُمَّ يُصَلِّي رَكْعَتَيْنِ وَهُوَ جَالِسٌ فَيَقْرَأُ وَيَرْكَعُ وَيُصَلِّي رَكْعَتَيْنِ بَيْنَ النِّدَاءِ وَالْإِقَامَةِ مِنْ صَلَاةِ الصُّبْحِ» تَابَعَهُ جَعْفَرُ بْنُ رَبِيعَةَ  

[Machine] He heard Aisha say that the Prophet of Allah ﷺ used to pray thirteen rak'ahs every night, standing for nine rak'ahs, sitting for two rak'ahs, then he would wait until the first adhan of Fajr and then he would stand and pray two rak'ahs. Abu Abdur-Rahman said that Sa'id entered between Jafar and Abu Salamah fighting each other.  

أَنَّهُ سَمِعَ عَائِشَةَ تَقُولُ كَانَ نَبِيُّ اللهِ ﷺ «يُصَلِّي كُلَّ لَيْلَةٍ ثَلَاثَ عَشْرَةَ رَكْعَةً تِسْعًا قَائِمًا وَرَكْعَتَيْنِ وَهُوَ جَالِسٌ ثُمَّ يُمْهِلُ حَتَّى يُؤَذِّنَ بِالْأَوَّلِ مِنَ الصُّبْحِ قَامَ فَرَكَعَ رَكْعَتَيْنِ» قَالَ أَبُو عَبْدِ الرَّحْمَنِ أَدْخَلَ سَعِيدٌ بَيْنَ جَعْفَرٍ وَبَيْنَ أَبِي سَلَمَةَ عِرَاكُ بْنُ مَالِكٍ  

[Machine] "The Messenger of Allah, ﷺ , prayed the evening prayer, then he prayed eight units of prayer standing, two units sitting, and two units between the two calls to prayer, and he did not skip them. Sa'eed bin Abi Sa'eed al-Maqburi and Abdullah bin Abi Labid opposed him in this, and they narrated it from Abu Salamah, but they did not mention the two units of prayer."  

«صَلَّى رَسُولُ اللهِ ﷺ الْعِشَاءَ ثُمَّ صَلَّى ثَمَانِ رَكَعَاتٍ قَائِمًا وَرَكْعَتَيْنِ جَالِسًا وَرَكْعَتَيْنِ بَيْنَ النِّدَاءَيْنِ وَلَمْ يَكُنْ يَدَعُهُمَا» خَالَفَهُمَا سَعِيدُ بْنُ أَبِي سَعِيدٍ الْمَقْبُرِيُّ وَعَبْدُ اللهِ بْنُ أَبِي لَبِيدٍ فَرَوَيَاهُ عَنْ أَبِي سَلَمَةَ وَلَمْ يَذْكُرَا الرَّكْعَتَيْنِ  

That he asked ʿAisha "How was the prayer of Messenger of Allah ﷺ in the month of Ramadan?" She replied, "He used not to pray more than eleven rakʿat whether in Ramadan or in any other month. He used to offer four rakʿat, let alone their beauty and length, and then four rakʿat, let alone their beauty and length. Afterwards he would offer three rakʿat. I said, 'O Messenger of Allah ﷺ! Do you go to bed before offering the witr prayer?' He said, 'My eyes sleep, but my heart does not sleep."' (Using translation from Bukhārī 3569)   

عَنْ صَلَاةِ رَسُولِ اللهِ ﷺ؟ قَالَتْ مَا كَانَ رَسُولُ اللهِ ﷺ يَزِيدُ فِي رَمَضَانَ وَلَا غَيْرِهِ عَلَى إِحْدَى عَشْرَةَ رَكْعَةً «يُصَلِّي أَرْبَعًا فَلَا تَسْأَلْ عَنْ حُسْنِهِنَّ وَطُولِهِنَّ ثُمَّ يُصَلِّي أَرْبَعًا فَلَا تَسْأَلْ عَنْ حُسْنِهِنَّ وَطُولِهِنَّ ثُمَّ يُصَلِّي ثَلَاثًا»  

[Machine] Regarding the fast of the Messenger of Allah ﷺ , it was said that he used to fast most of the month of Sha'ban, except for a few days. I asked about his night prayer, and it was said that his night prayer consisted of thirteen units of prayer, including the two units of Fajr.  

عَنْ صِيَامِ رَسُولِ اللهِ ﷺ فَقَالَتْ كَانَ يَصُومُ شَعْبَانَ إِلَّا قَلِيلًا وَسَأَلْتُهَا عَنْ صَلَاةِ اللَّيْلِ؟ فَقَالَتْ كَانَتْ صَلَاتُهُ بِاللَّيْلِ فِي شَهْرِ رَمَضَانَ وَغَيْرِهِ ثَلَاثَ عَشْرَةَ رَكْعَةً مِنْهَا رَكْعَتَا الْفَجْرِ