Or HaChaim on Genesis 20:10/אור החיים על בראשית כ׳:י׳

1 ויאמר אבימלך. Avimelech said. Seeing that the previous verse had been a rebuke only, he now switched to a question. This is why the sentence had to begin once more with the words: "Avimelech said," though Abraham had not yet responded to the accusation. Avimelech now conceded that he did not consider Abraham capable of wanting to harm him intentionally.