'Heir' in the Bible

And Abram said, Behold, to me thou hast given no seed: and, lo, one born in my house is mine heir.

And, behold, the word of Jehovah came unto him, saying, This man shall not be thine heir; But he that shall come forth out of thine own bowels shall be thine heir.

Wherefore she said unto Abraham, Cast out this handmaid and her son. For the son of this handmaid shall not be heir with my son, even with Isaac.