Not graded
Hisn al-Muslim (Fortress of the Muslim) 224
قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم: ((لاَ تَدْخُلُوا الْجَنَّةَ حَتَّى تُؤْمِنُوا، وَلاَ تُؤْمِنُوا حَتَّى تَحَابُّوا، أَوَلاَ أَدُلُّكُم عَلَى شَيْءٍ إِذَا فَعَلْتُمُوهُ تَحَابَبْتُم، أَفْشُوا السَّلاَمَ بَيْنَكُمْ)).
(The Messenger of Allah said: ‘You shall not enter paradise until you believe, and you shall not believe until you love one another. Shall I not inform you of something, if you were to act upon it, you will indeed achieve mutual love for one another? Spread the greeting amongst yourselves.)
Cited in Hisn al-Muslim (Fortress of the Muslim) (No. 224).