Sarah, my master’s wife, gave birth to a son when she was old, and my master has given everything he owns to that son.
Abraham left everything he owned to Isaac.
So Sarah said to Abraham, “Throw out this slave woman and her son. Her son should not inherit anything; my son Isaac should receive it all.”
Abraham was almost a hundred years old, much past the age for having children, and Sarah could not have children. Abraham thought about all this, but his faith in God did not become weak.