Bomb disposal experts summoned to the house in Tambon Bannang Sareng in Muang Yala had the device deactivated by 8.45am.
The bomb was a M26 grenade with the safety pin removed and the spring lever held in place with elastic bands.
Police said a burning cigarette placed atop the elastic bands to trigger the grenade had gone out before it could burn through them and release the lever.
The house owner, rubber tapper Muhammad Dolohsae, 30, found the grenade and alerted police.
Soldiers from Yala Taskforce 12 took Marobi Sola into custody for interrogation. He had been seen walking around the house earlier in the morning.