|H. Krisp/Creative Commons|
The cobra bit him first. The BBC reported his motive this way:
BBC News - Farmer bites cobra to death in Nepal:
"A Nepali farmer who was bitten by a cobra in his rice paddy field has killed the snake by repeatedly biting it in return.
"A snake charmer told me that if a snake bites you, bite it until it is dead and nothing will happen to you," Mohammed Salmodin told the BBC."
But a report in Reuters mentions a different motive:
"I could have killed it with a stick but bit it with my teeth instead because I was angry."
Mohammed Salmodin then went back to work until his family pressured him to get help. Remind me not to make this guy angry.
Incidentally, I knew a family who had eaten cobra. They said it was good in soup.
(Thanks to Croconut for the news tip)