What are people who prractice judaism believe they are descendants of who?

Jews, Christians, and Muslims agree they are all descendant from Abraham. However, Christians and Jews specifically believe they are descendant from Isaac, Abraham's second son who is believed to be the son God promised Abraham and his wife. The Muslims believe they are specifically descendant from Ishmael, Abraham's first son. Thus the line of Isaac and the line of Ishmael continue to fight over the Holy Land. To understand this better, read from Genesis, ch. 16 and on. (This in the Old Testament/ Torah [The book of the Jews or the first half of The Bible]. I am not sure if this is included in the Koran [The book of the Muslims]).