in the Bible denotes a female conjugally united to a man, but in
a relation inferior to that of a wife. Among the early Jews,
from various causes, the difference between a wife and a
concubine was less marked than it would be amongst us. The
concubine was a wife of secondary rank. There are various laws
recorded providing for their protection (Ex. 21:7; Deut.
21:10-14), and setting limits to the relation they sustained to
the household to which they belonged (Gen. 21:14; 25:6). They
had no authority in the family, nor could they share in the
household government.

The immediate cause of concubinage might be gathered from the
conjugal histories of Abraham and Jacob (Gen. 16;30). But in
process of time the custom of concubinage degenerated, and laws
were made to restrain and regulate it (Ex. 21:7-9).

Christianity has restored the sacred institution of marriage
to its original character, and concubinage is ranked with the
sins of fornication and adultery (Matt. 19:5-9; 1 Cor. 7:2).