Genesis 20:17

17.So Abraham prayed. In two respects the wonderful favor of God towards Abraham was apparent; firsts that, with outstretched hand, He avenged the injury done to him; and, secondly, that, through Abraham’s prayer, He became pacified towards the house of Abimelech. It was necessary to declare, that the house of Abimelech had been healed in answer to Abraham’s prayers; in order that, by such a benefit, the inhabitants might be the more closely bound to him. A question, however, may be agitated respecting the kind of punishment described in the expression, the whole house was barren. For if Abraham had gone into the land of Gerar, after Sarah had conceived, and if the whole of what Moses has here related was fulfilled before Isaac was born, how was it possible that, in so short a time, this sterility should be manifest? If we should say, that the judgment of God was then made plain, in a manner to us unknown, the answer would not be inappropriate. Yet I am not certain, that the series of the history has not been inverted. The more probable supposition may seem to be, that Abraham had already been resident in Gerar, when Isaac was promised to him; but that the part, which had before been omitted, is now inserted by Moses. Should any one object, that Abraham dwelt in Mamre till the destruction of Sodom, there would be nothing absurd in the belief, that what Moses here relates had taken place previously. Yet, since the correct notation of time does little for the confirmation of our faith, I leave both opinions undecided.