Who came to visit Okonkwo during the second year of exile and why?

Okonkwo's best friend Obierika comes to visit Okonkwo in Mbanta during the second year of exile. He comes to see how Okonkwo is doing, and to give him the money he received from selling Okonkwo's yams. He also tells Okonkwo of the slaughter of Abame.