كتاب الإيمان
1  
The Book of Faith
(22)
Chapter: Clarifying that no one will enter paradise but the believers; loving the believers is part of faith and spreading Salam is a means of attaining that
(22)
باب بَيَانِ أَنَّهُ لاَ يَدْخُلُ الْجَنَّةَ إِلاَّ الْمُؤْمِنُونَ وَأَنَّ مَحَبَّةَ الْمُؤْمِنِينَ مِنَ الإِيمَانِ وَأَنَّ إِفْشَاءَ السَّلاَمِ سَبَبٌ لِحُصُولِهَا
Sahih Muslim 54 b

Zuhair b. Harb said:

Jarir reported on the authority of A'mash with this chain of transmitters that the Messenger of Allah (ﷺ) observed: By him in Whose hand is my life, you shall not enter Paradise unless you believe. The rest of the hadith is the same as narrated by Abd Mu'awiya and Waki'.
وَحَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، أَنْبَأَنَا جَرِيرٌ، عَنِ الأَعْمَشِ، بِهَذَا الإِسْنَادِ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ وَالَّذِي نَفْسِي بِيَدِهِ لاَ تَدْخُلُونَ الْجَنَّةَ حَتَّى تُؤْمِنُوا ‏"‏ ‏.‏ بِمِثْلِ حَدِيثِ أَبِي مُعَاوِيَةَ وَوَكِيعٍ ‏.‏
Reference : Sahih Muslim 54b
In-book reference : Book 1, Hadith 102
USC-MSA web (English) reference : Book 1, Hadith 97
  (deprecated numbering scheme)