1 Abraham took another wife, whose name was Keturah.
2 She bore him six sons: Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah.
Left: Hagar and Ishmael; Center: Abraham, Sarah, and Isaac; Right: Keturah and her six sons
Abraham dies, giving all his possessions to Isaac
5-7 Abraham died when he was 175 years old. He gave everything he had to Isaac, except for some gifts to his sons who were born to his concubines, who he sent away to live in the east country.
9 Isaac and Ishmael buried Abraham in the same cave in which Sarah was buried.
21 Rebekah was barren, so Isaac asked God for help to get her pregnant. 22 So God made her pregnant, and she conceived twins. 23 God said to Rebekah,
Two nations are in your womb. The older will serve the younger.
25 Esau was the first to be born. He was red and hairy all over. 26 When the other came out he grabbed on to Esau's heel. He was named Jacob. 27 Esau was a hunter, while Jacob was a plain man who lived in tents. 28 Isaac loved Esau because Esau was a hunter and Isaac loved venison. But Rebekah loved Jacob.
Esau sells his inheritance for a bowl of lentil soup
29 One day when Jacob was making soup, Esau came in from the field. 30 He was tired and hungry, so he said to Jacob,
Please feed me some of that soup because I'm tired and hungry.
31 Jacob said, "Okay, if you'll sell me your birthright."
32 Esau said, "Well, since I'm about to die of hunger, what good will my birthright do me?"
Abraham gave everything he owned to Isaac -- ignoring his other sons (Ishmael, Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah), as well as God knows how many nameless and unmentioned daughters, and the wives and concubines themselves.
Abraham's concubines (v.6)
How many concubines did Abraham have? The Bible mentions Hagar and Keturah, but were there others?
Isaac loved Esau ... But Rebekah loved Jacob (v.28)
God, like Rebekah, loved Jacob more than Esau. In fact, according to Malachi 1:3 and Romans 9:13, he hated Esau.
No reason is given for why one son is loved and the other is hated. But since God chose to act this way, it must have been as an example for parents to follow.