Mr Mwangi alleged that his attacker, who is also said to be aged 39, accused him of having an affair with his 56-year-old girlfriend. Both men are married.
He said the enraged neighbour attacked him with a panga, a knife and a stick.
“He attacked me using a panga and a knife, saying I would learn my lesson for having an affair with his girlfriend. Since I was drunk, he overpowered me to the ground before stabbing me several times in the legs, hands and head. He then cut off my genitals using the knife. It was very painful,” said Mwangi.