ChristianAnswers.Net WebBible Encyclopedia
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). But in process of time, the custom of concubinage degenerated, and laws were made to restrain and regulate it (Ex. 21:7-9).