A 21-year-old woman has been stabbed with a kitchen knife in the stomach and kidney after revellers gathered at a unit in Sydney.

She was part of a group of people who were drinking at a hotel on Curtin Crescent, Maroubra, on Friday afternoon.

They were joined by an unknown woman, aged between 18 to 25, who returned with them a few hours later to a nearby unit on New Orleans Crescent.

But she began to argue with the group shortly after 10pm and grabbed a knife from a knife block.

She then used it to stab the 21-year-old woman in the abdomen and kidney before running away.