Genesis 25:5

Gave all that he had unto Isaac - His principal flocks, and especially his right to the land of Canaan, including a confirmation to him and his posterity of whatever was contained in the promises of God.

Abraham makes Isaac his heir Genesis 24:36. He gives portions to the sons of the concubines during his lifetime, and sends them away to the East. Ishmael had been portioned off long before Genesis 21:14. The East is a general name for Arabia, which stretched away to the southeast and east of the point where Abraham resided in the south of Palestine. The northern part of Arabia, which lay due east of Palestine, was formerly more fertile and populous than now. The sons of Keturah were probably dismissed before they had any children. Their notable descendants, according to custom, are added here before they are dismissed from the main line of the narrative.

25:5 And Abraham gave all that he had to Isaac - As he was bound to do in justice to Sarah his first wife, and to Rebekah who married Isaac upon the assurance of it.