Nusayr (may Allah have mercy on him), the freed slave of Sayyiduna Mu'awiyah (may Allah be pleased with him), said that the Messenger of Allah (peace and blessings be upon him) forbade harmful division.
This is mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20448