When the emigrants came to Medina, the Ansar used to be the heir of the emigrants (and vice versa) instead of their own kindred by blood (Dhawl-l-arham), and that was because of the bond of brotherhood which the Prophet had established between them, i.e. the Ansar and the emigrants. But when the Divine Verse:--

'And to everyone We have appointed heirs,' (4.33) was revealed, it cancelled the other, order i.e. 'To those also, to whom Your right hands have pledged.'