نسخ الرابط 
مثار: حافز أو مدعاة أو سبب: كان الأمر مثار جدل ونزاع
🦴 Bone of contention: the most probable origin of this phrase comes from the idea of two dogs fighting over a bone. Neither is willing to give up his position, and thus the fight is ongoing and the bone is seen as the specific point of contention.
