Sahih Bukhari Volume 8, Book 80, Hadith Number 739.

Narrated By Ibn ‘Abbas : Regarding the Holy Verse: “And to everyone, We have appointed heirs…” (4.33) And: “To those also to Whom your right hands have pledged.” (4.33)

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.”