Where and with whom was Abraham buried?
Abraham was buried in the cave of Mephila. His sons Isaac and Ishmael both participated in his burial; Ishmael came and associated himself with Isaac for the burial. He died at 175, an old man full of years and gathered to his people.
Les explains that Abraham lived to be 175 years old. He had married Keturah around age 160, so he was probably married to her for about 15 more years. Then Abraham gave up the ghost and died in a good old age, full of years, and was gathered to his people. His sons Isaac and Ishmael were still in contact, so Ishmael knew when Abraham died and came to associate himself with Isaac in the burial of Abraham in the cave of Mephila. Earlier, God had established His covenant with Isaac, and the other sons of Abraham were given gifts but sent away, unable to partake of the covenant promises.
And his sons Isaac and Ishmael buried him in the cave of Machpelah, in the field of Ephron the son of Zohar the Hittite, which is before Mamre;