(4) باب النَّهْىِ عَنِ ابْتِدَاءِ، أَهْلِ الْكِتَابِ بِالسَّلاَمِ وَكَيْفَ يَرُدُّ عَلَيْهِمْ
This hadith has been narrated on the authority of Ibn 'Umar through another chain of transmitters with a slight variation of wording.
Reference: Sahih Muslim 2164 b
In-book reference: Book 39, Hadith 10
USC-MSA web (English) reference(deprecated numbering scheme): Book 26, Hadith 5383