During interrogation, the accused persons claimed that Jacky used to beat up Kamal.
Two brothers were arrested for allegedly killing a person who used to assault one of them in north Delhi's Sadar Bazar area, police said on Saturday.
The accused have been identified as Ram, 34 and Kamal, 40, residents of Basti Julahan, Sadar Bazar, they said.
According to police, complainant Suresh Kumar reported that he heard some noise coming in from the street on Friday around 9:30 pm.
He reached Sarla Chowk in Basti Julahan, where he saw that Ram was quarrelling with Kumar's brother-in-law Jai Kishan alias Jacky, 34, police said.
During the quarrel, Ram went to his home and immediately returned with a knife along with his elder brother Kamal.
As Kamal caught Jacky, Ram stabbed him in his stomach. Meanwhile, a local resident Saurav tried to save Jacky but Ram attacked him as well with the knife, a senior police officer said.
Saurav got down and the knife hit him at the backside of his neck and ran away to save his life.
Jacky also tried to escape but the accused pushed him onto the road. They kicked him multiple times and then fled from the spot, the officer said.
Jacky was rushed to Hindu Rao Hospital, where he was declared brought dead, while Sourav is out of danger, police said.
"During investigation, police arrested Ram and Kamal," Deputy Commissioner of Police (north) Anto Alphonse said.
During interrogation, the accused persons claimed that Jacky used to beat up Kamal. On Friday also, Jacky had a quarrel with Kamal and beat him due to which Kamal sustained a minor head injury, the senior police officer said.
Meanwhile, Ram came and started a quarrel with Jacky. In order to take revenge, Ram went home and brought a kitchen knife. Kamal also accompanied him and they both stabbed Jacky and escaped from the spot, police said.
Police said Jacky was previously involved in four criminal cases, including attempt to murder, assault, eve teasing, Arms Act, etc.