Caliphate legitimacy through kinship and companionship
Nahj al-Balāgha|Volume 1|Book 3|Chapter 190
١٩٠. وَقَالَ (عليه السلام): وَاعَجَبَاهُ! أَتَكُونُ الْخِلاَفَةَ بِالصَّحَابَةِ وَلاَتَكُونُ بِالصَّحَابةِ وَالْقَرَابَةِ؟
190. Amīr al-mu’minīn, peace be upon him, said: How strange? Could the caliphate be through the (Prophet’s) companionship but not through (his) companionship and (his) kinship?