Sunan Abi Dawud 1366
Khalid al-Juhani said:
I shall watch the prayer of the Messenger of Allah (ﷺ) at night. I slept at the threshold of his door or of his tent. The Messenger of Allah (ﷺ) prayed two light rak'ahs, and then prayed two long, long, long rak'ahs. He then prayed two rak'ahs that were not so long as the two rak'ahs before them ; he then prayed two rak'ahs that were less in duration, than the rak'ahs before them; again he prayed two rak'ahs that were less in length then the preceding rak'ahs; he then prayed two rak'ahs that were less in length than the previous rak'ahs. This made altogether thirteen rak'ahs.
حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي بَكْرٍ، عَنْ أَبِيهِ، أَنَّ عَبْدَ اللَّهِ بْنَ قَيْسِ بْنِ مَخْرَمَةَ، أَخْبَرَهُ عَنْ زَيْدِ بْنِ خَالِدٍ الْجُهَنِيِّ، أَنَّهُ - قَالَ - لأَرْمُقَنَّ صَلاَةَ رَسُولِ اللَّهِ صلى الله عليه وسلم اللَّيْلَةَ، قَالَ ‏:‏ فَتَوَسَّدْتُ عَتَبَتَهُ أَوْ فُسْطَاطَهُ، فَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم رَكْعَتَيْنِ خَفِيفَتَيْنِ، ثُمَّ صَلَّى رَكْعَتَيْنِ طَوِيلَتَيْنِ طَوِيلَتَيْنِ طَوِيلَتَيْنِ، ثُمَّ صَلَّى رَكْعَتَيْنِ وَهُمَا دُونَ اللَّتَيْنِ قَبْلَهُمَا، ثُمَّ صَلَّى رَكْعَتَيْنِ دُونَ اللَّتَيْنِ قَبْلَهُمَا، ثُمَّ صَلَّى رَكْعَتَيْنِ دُونَ اللَّتَيْنِ قَبْلَهُمَا، ثُمَّ صَلَّى رَكْعَتَيْنِ دُونَ اللَّتَيْنِ قَبْلَهُمَا، ثُمَّ أَوْتَرَ، فَذَلِكَ ثَلاَثَ عَشْرَةَ رَكْعَةً ‏.‏