'Heir' in the Bible

Abram said, "Behold, to me you have given no seed: and, behold, one born in my house is my heir."

Behold, the word of Yahweh came to him, saying, "This man will not be your heir, but he who will come forth out of your own body will be your heir."

Therefore she said to Abraham, "Cast out this handmaid and her son! For the son of this handmaid will not be heir with my son, Isaac."