Genesis 25:1

Five and thirty years Abraham lived after the marriage of Isaac, and all that is recorded concerning him during that time lies here in a very few verses; we hear no more of God's extraordinary appearances to him or trials of him; for all the days even of the greatest saints are not eminent; some slide on silently; such were these last days of Abraham. We have here an account of his children by Keturah, another wife, whom he married after the death of Sarah. He had buried Sarah, and married Isaac, the two dear companions of his life, and was now solitary; his family wanted a governess, and it was not good for him to be thus alone; he therefore marries again. By Keturah he had six sons, in whom the promise made to Abraham, concerning the great increase of his posterity, was in part fulfilled. The strength he received by the promise still remained in him, to show how much the virtue of the promise exceeds the power of nature.