Abraham - the father of Israel
Abram's name was changed to Abraham when God revealed himself to Abram and gave him the promise that he would make him into a great nation. He is called the Father of Israel because he is the literal progenitor of Jacob; named Israel.
- Abraham is not simply the father of Jacob, but the Father of the revelation of God to the people known as Israel. God made a promise to Abraham
Jacob was a grandson of Abraham who obtained the covenant from God. The promise was passed to Jacob, who was renamed Israel. His twelve sons became the fathers of the twelve tribes of Israel. Sometime his name Jacob is used and sometimes his name Israel is used.
Mt 3:9 And think not to say within yourselves, We have Abraham to [our] father: for I say unto you, that God is able of these stones to raise up children unto Abraham.