The man and woman, both 26, were in the bedroom of their flat in Kilmuir Crescent in Thornliebank, Glasgow, when they heard someone at the door at about 3.45am on Sunday.
Four men burst in to the property and seriously assaulted the man with a bladed weapon.
He was treated at the Victoria Infirmary for injuries to his arm and abdomen but has since been discharged.
Strathclyde Police said they do not believe it was a random attack.
All the men are described as being aged between 30 and 40.