كتاب الطلاق
18  
The Book of Divorce
(4)
Chapter: Giving one's wife the choice does not count as a divorce, unless it is intended as such
(4)
باب بَيَانِ أَنَّ تَخْيِيرَ امْرَأَتِهِ لاَ يَكُونُ طَلاَقًا إِلاَّ بِالنِّيَّةِ ‏‏
Sahih Muslim 1476 b
The above hadith has likewise been narrated through another chain.
وَحَدَّثَنَاهُ الْحَسَنُ بْنُ عِيسَى، أَخْبَرَنَا ابْنُ الْمُبَارَكِ، أَخْبَرَنَا عَاصِمٌ، بِهَذَا الإِسْنَادِ ‏.‏ نَحْوَهُ ‏.‏
Reference : Sahih Muslim 1476b
In-book reference : Book 18, Hadith 32
USC-MSA web (English) reference : Book 9, Hadith 3499
  (deprecated numbering scheme)