´It was narrated from Ibn 'Umar that :` The Prophet [SAW] said: "Do not revert to disbelievers after I am gone, striking the necks of one another (killing one another)."
Hadith Referenceسنن نسائي / كتاب تحريم الدم / 4130
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:متفق عليه