"Nitish Kumar is not Bihar. As far as the honour of Bihar people is concerned, he has insulted them when being Bihar chief minister, he has refused to offer food to Narendra Modiji after inviting him for dinner," Paswan said in a statement.
"People of Bihar have exposed what is the strength of Nitish Kumar in the Lok Sabha. They will again teach a lesson to him during the assembly elections," the LJP chief said.
In the letter, which was released on social media sites Facebook and Twitter, Kumar said the comment was unbecoming of the office he holds.
"Your words have been taken as an insult by a large section of the people of the state and beyond. Most of us also feel that coming from you, the comment is rather unbecoming of the office you hold," he said.