TSK · Genesis 24:36

God said to Abraham, "As for Sarai your wife, you shall not call her name Sarai, but her name will be Sarah.

Now Abraham and Sarah were old, well advanced in age. Sarah had passed the age of childbearing.

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."

Without being weakened in faith, he didn't consider his own body, already having been worn out, (he being about a hundred years old), and the deadness of Sarah's womb.