What was Yitzchak's question?
Targum Yonasan: Why do you come to me, that I should pray for you? You hated me, and drove me out! 1
Ohr ha'Chayim: Surely you do not fear that I permit Avraham's Shevu'ah to you. Since he did not do so, I cannot. If it is to help me, to let me return; all of you hated me due to envy. Surely this did not change!
Malbim: Did you come for peace, or for war? It cannot be for Shalom, for you hated me. It cannot be for war, for you sent me away. Had you wanted to fight me, you would have done so when I was with you!
Ha'amek Davar: Surely you did not come for friendship, for you hated me!
Avimelech had told Yitzchak, "Lech me'Imanu" (26:16). Why did Yitzchak imply that he had said, 'Lech me'Itanu'?
Ha'amek Davar: "Me'Imanu" implies that you should not be so close - the Bris did not obligate letting you be so close - but you need not go far away. Yitzchak replied "Atazmta Mimenu" was a mere pretext. You wanted me to go 'me'Itanu' - not to be in your city at all!