The incident took place in Nawazgarh village under Warsaliganj police station last night when the accused persons barged into the house of Gorelal Manjhi and beat him up.
Manjhi had earlier refused to work for free in their field.
When Manjhi's wife Kari Devi tried to save her husband, she was also assaulted, the police said.
A case has been lodged on the basis of a statement by the couple who was admitted to hospital in a badly injured condition.