Al-Kāfi - Volume 6 > The Two Arbitrators in the case of Discord
Hadith #3

حُمَيْدُ بْنُ زِيَادٍ عَنِ ابْنِ سَمَاعَةَ عَنْ عَبْدِ اللَّهِ بْنِ جَبَلَةَ عَنْ عَلِيِّ بْنِ أَبِي حَمْزَةَ عَنْ أَبِي بَصِيرٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) فِي قَوْلِ اللَّهِ عَزَّ وَ جَلَّ فَابْعَثُوا حَكَماً مِنْ أَهْلِهِ وَ حَكَماً مِنْ أَهْلِها قَالَ الْحَكَمَانِ يَشْتَرِطَانِ إِنْ شَاءَا فَرَّقَا وَ إِنْ شَاءَا جَمَعَا فَإِنْ جَمَعَا فَجَائِزٌ وَ إِنْ فَرَّقَا فَجَائِزٌ

3. Humayd ibn Ziyad has narrated from ibn Sama‘ah from ‘Abd Allah ibn Jabalah from Ali ibn abu Hamzah from abu Basir who has said the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about the words of Allah, most Majestic, most Glorious, ‘If you are afraid of discord between them then send one arbitrators from his people and another from her people.’ (4:35) He (the Imam) said, ‘The two arbitrators stipulate upon them that their decision to separate or to bring them together must be treated binding and on that basis if they separate or bring them together it is permissible.’”