The occasion of becoming a Bar Mitzvah calls for Aaron to read the Torah (five books of Moses) and a Haftarah portion, which is from the Book of Prophets. Aaron's Torah reading is Chayei Sarah, which is the 5th weekly Torah portion in the annual cycle.
This Torah reading deals with a burial place for Sarah, wife of Abraham. Abraham asked the Hittites to intercede for him with Ephron, son of Zohar, to sell Abraham the cave of Machpelah at full price. Ephron offered to give Abraham for free the field and the cave that was in it, but Abraham insisted on paying the price of the land. Ephron named the value of the land at 400 shekels of silver and Abraham accepted Ephron's terms, gave him the silver, and purchased the land. Abraham buried Sarah in the cave.
Abraham's purchase of the land - rather than accepting it for free - established his right to the land, which some scholars say establishes the Jewish peoples' claims and linkage to the Holy Land. He bought the land rather than accept it as a gift.
The cave of Machpelah is a series of subterranean caves located in the ancient city of Hebron. This is the second holiest site for Jews, and tradition maintains that it is the burial site of Abraham and Sarah, Isaac and Rebecca, and Jacob and Leah.