Tha'labah al-Himmani said: We came to Sayyiduna Ali (may Allah be pleased with him) at a place called al-Rahbah, and he said: If you would not fight among yourselves, I would divide al-Sawad among you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18373