Charles Ellicott Commentary 2 Samuel 20:3

"And David came to his house at Jerusalem; and the king took the ten women his concubines, whom he had left to keep the house, and put them in ward, and provided them with sustenance, but went not in unto them. So they were shut up unto the day of their death, living in widowhood." — 2 Samuel 20:3 (ASV)

Living in widowhood. —This was the necessary result, under the system of polygamy, of what had happened. The clause may be understood as “in widowhood of life,” as in our version, or “in widowhood of the living,” i.e., while their husband was living, as in the Chaldee.