'Heir' in the Bible

But Abram said, "O sovereign Lord, what will you give me since I continue to be childless, and my heir is Eliezer of Damascus?"

Abram added, "Since you have not given me a descendant, then look, one born in my house will be my heir!"

But look, the word of the Lord came to him: "This man will not be your heir, but instead a son who comes from your own body will be your heir."

So she said to Abraham, "Banish that slave woman and her son, for the son of that slave woman will not be an heir along with my son Isaac!"