Jackson Yongki, 58, was with his two sons at the age of 15 and 17 on his paddy field when a Bornean sun bear – who is a protected species – approached them around 7.30.
He told a local newspaper that the bear was trying to attack one of his sons, so he instinctively hit a piece of wood.
The animal managed to bite his left leg when Jackson, whose other leg was trapped in the mud, tried to get away.
He said the trio knew that the turtle was a protected species and did not intend to wound it or kill it.
"We hope that the relevant authorities will be able to record it quickly so that it does not enter the village area again," he said.
Jackson received a treatment at the Kampung Entilibon health clinic.
According to the report, a team from the Wildlife Rescue Unit and the Sepilok Bear Unit was sent to the scene to locate the animal.
The Bornean sun bear is a protected species under Schedule 1 of the Sabah Wildlife Enactment 1997.