The name of the Parshah, "Chayei Sarah," means "The life of Sarah" and it is found in Genesis 23:1.
Sarah dies at age 127 and is buried in the Machpelah Cave in Hebron, which Abraham purchases from Ephron the Hittite for four hundred shekels of silver.
Abraham’s servant Eliezer is sent, laden with gifts, to Charan, to find a wife for Isaac. At the village well, Eliezer asks G‑d for a sign: when the maidens come to the well, he will ask for some water to drink; the woman who will offer to give his camels to drink as well shall be the one destined for his master’s son.
Rebecca, the daughter of Abraham’s nephew Bethuel, appears at the well and passes the “test.” Eliezer is invited to their home, where he repeats the story of the day’s events. Rebecca returns with Eliezer to the land of Canaan, where they encounter Isaac praying in the field. Isaac marries Rebecca, loves her, and is comforted over the loss of his mother.
Abraham takes a new wife, Keturah (Hagar), and fathers six additional sons, but Isaac is designated as his only heir. Abraham dies at age 175 and is buried beside Sarah by his two eldest sons, Isaac and Ishmael.
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Abraham has the first child with Hagar. Abraham has 6 more children with Hagar.
Abraham blessed with one child with Sarah when he's 100 years old and this child will have a special mission which he will confirm by cheating on his father and brother.
Is not number of children with a particular woman considered to be a blessing?
What was special about Sarah that made her a chosen one?
Respectfully.
What great questions! Regarding the end of Abraham's life, G-d told him, "I want you to remarry even though you are on an extremely high spiritual level and you no longer think about the worldly at all. Not to satisfy your desires; they no longer have any meaning to you. I want you to publicize My greatness, to let people know that I can perform miracles and change the course of nature. When you were young, you could not have children. Now that you are 140 years old, you will have many children."
When a mortal king gives a friend a gift, he usually adds something to it each year. However, the additional gift is much smaller than the original one. When G-d gives a gift, His additions to it can be much greater than the original gift. G-d's original gift to Abraham was a single son. The addition was many children (Midrash Bereishis Rabbah 61:4)
We see earlier in the story that Sarah told Abraham, "Drive out this slave together with her son. The son of this slave will not share the inheritance with my son Isaac" (Genesis 21:10) G-d then told Abraham, "Abide by everything Sarah tells you" (21:12). Rashi explains that we learn from here that Abraham was inferior to Sarah in prophecy.