كتاب صلاة المسافرين وقصرها
6  
The Book of Prayer - Travellers
(25)
Chapter: Encouragement to pray qiyam during Ramadan, which is Tarawih
(25)
باب التَّرْغِيبِ فِي قِيَامِ رَمَضَانَ وَهُوَ التَّرَاوِيحُ ‏
Sahih Muslim 762 c

Shu'ba reported this hadith with the same chain of transmitters, but he made no mention that Shu'ba was in doubt and what follows subsequently.

وَحَدَّثَنِي عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ ‏.‏ نَحْوَهُ وَلَمْ يَذْكُرْ إِنَّمَا شَكَّ شُعْبَةُ ‏.‏ وَمَا بَعْدَهُ ‏.‏
Reference : Sahih Muslim 762c
In-book reference : Book 6, Hadith 215
USC-MSA web (English) reference : Book 4, Hadith 1670
  (deprecated numbering scheme)