Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: The Messenger of Allah (peace and blessings be upon him) established brotherhood between his Companions, and on that basis they began to inherit from one another, until this verse was revealed: "And blood relatives are more entitled to one another" [Surah al-Ahzab: 6]. Then they began to inherit on the basis of lineage.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11698