Keturah, Abraham's concubine - Abraham's pilegesh, or wife of the second rank; she was neither whore, harlot, nor concubine, in our sense of these words.
Keturah, Abraham‘s concubine - This passage, and Genesis 25:6, sufficiently prove that the position of Keturah was not that of the full wife, but of the “secondary” or “concubine wife” Judges 19:1 so common among Orientals.