Then again Abraham took a wife, and her name was Keturah. This woman was not a concubine during the lifetime of Sarah, but his wife by a second marriage, although she did not hold the status of the mother of the promised Seed, she was not included in the Messianic promise.
Related Commentaries of Genesis 25:1
Genesis 25:1
1 Then again Abraham took a wife, and her name was Keturah.