Faizal Mokhtar was fined RM6,000 after he pleaded guilty to threatening his mother, Syarifah Alawiyah Engku Ambak, 63, with a knife at 3am at their house in Kampung Bukit Tok Beng here on Jan 15.
However, he could not pay the fine and magistrate Nor Azizah Yusof ordered that he be jailed for eight months.
Earlier, Nor Azizah told him that it was unbecoming and very disrespectful for a son to threaten his mother.
On the day of the incident, Faizal was watching television in the living room. He became violent after his mother asked him to lower the volume.
The mother ran into her bedroom after Faizal threatened her with a kitchen knife. She later lodged a police report.
Faizal was detained at his home on Jan 17 and tested positive for methamphetamine.
Assistant Superintendent Ngaim Ooi Ming prosecuted while Faizal was unrepresented.