(43) The Book of Virtues
كتاب الفضائل
(9) Chapter: The Cistern Of Our Prophet (SAW) And Its Attributes
(9) باب إِثْبَاتِ حَوْضِ نَبِيِّنَا صلى الله عليه وسلم وَصِفَاتِهِ ‏‏
Sahih Muslim 2297 b 

The hadith has been narrated on the authority ot al-A'mash with the same chain of transmitters but no mention is made of:

" They are my companions; they are my companions."
وَحَدَّثَنَاهُ عُثْمَانُ بْنُ أَبِي شَيْبَةَ، وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ، عَنْ جَرِيرٍ، عَنِ الأَعْمَشِ، بِهَذَا الإِسْنَادِ ‏.‏ وَلَمْ يَذْكُرْ ‏ "‏ أَصْحَابِي أَصْحَابِي ‏"‏ ‏.‏
Reference : Sahih Muslim 2297b
In-book reference : Book 43, Hadith 40
USC-MSA web (English) reference : Book 30, Hadith 5691
  (deprecated numbering scheme)