Al-Kāfi - Volume 2 > A Believer Finds Comfort With Another Believer
Hadith #1

1ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ مُحَمَّدِ بْنِ عِيسَى بْنِ عُبَيْدٍ عَنْ يُونُسَ عَمَّنْ ذَكَرَهُ عَنْ أَبِي عَبْدِ الله (عَلَيهِ السَّلام) قَالَ إِنَّ الْمُؤْمِنَ لَيَسْكُنُ إِلَى الْمُؤْمِنِ كَمَا يَسْكُنُ الظَّمْ‏آنُ إِلَى الْمَاءِ الْبَارِدِ.

1. Ali ibn Ibrahim has narrated from Muhammad ibn ‘Isa ibn ‘Ubayd from Yunus from those he has mentioned (in his book) from abu ‘Abd Allah (a.s.) who has said the following: “A believer finds comfort with another believer just as a thirsty person finds relief from cool water.”