A 40-year-old man got into an argument with a younger man whom he suspected of having an affair with his wife, and stabbed the victim in the stomach.
The 31-year-old victim was bleeding when police arrived at the scene on Tuesday afternoon. Officers later arrested the older man.
Chinese evening daily Lianhe Wanbao reported that the incident happened at about 4.40pm that day at Block 677, Woodlands Avenue 6.
Witnesses said the victim was talking to a woman at the block's void deck when the older man confronted them. It emerged that the woman was the older man's wife, and he suspected she was having an affair with the victim.
The man got increasingly agitated and became aggressive. The victim tried to leave the scene, but the man gave chase with a knife that he had concealed in a yellow bag.
The victim fell to the ground after he was stabbed. The older man continued attacking him, slashing him on the left hand.
The woman then stepped in to break up the fight by grabbing her husband, who then threw the bag on the floor, exposing the fruit knife that he had used.
The victim, who was bleeding profusely, received help from the woman and three passers-by.
He was taken conscious to Khoo Teck Puat Hospital.
One witness told Lianhe Wanbao that further conversations between the husband and wife revealed they have two children, and that the woman intends to seek a divorce.
A police spokesman said the case was classified as one of voluntarily causing grievous hurt with dangerous means. Investigations are ongoing.