The Pulpit Commentary - Genesis 20:13
And it came to pass, when God caused me to wander (or to go on pilgrimages) from my father's house ,—Elohim, usually construed with a singular verb, is here joined with a verb in the plural, as an accommodation to the polytheistic stand-point of Abimelech (Keil), as a proof that Elohim is to be viewed as a Pluralis Majestaticus (Kalisch), as referring to the plurality of Divine manifestations which Abraham had received (Lange), as showing that Elohim here signifies angels (Calvin), or,... read more
The Pulpit Commentary - Genesis 20:12
And yet indeed she is my sister . This was the second of the patriarch's extenuating pleas, that he had not exactly lied, having uttered at least a half truth. She is the daughter of my father (Terah), But not the daughter of my mother. That Sarah was the grand-daughter of Terah, i.e. the daughter of Haran, and sister of Lot, in other words, Iscah, has been maintained. That she was Terah's niece, being a brother's daughter adopted by him, has received some support (Calvin); but there seems... read more