Midras 1 Raja-raja 18:7: Aggadat Bereshit

[4] Another interpretation: Vision of Obadiah: What did Obadiah see as a reason to punish Edom? Rather, the Holy One, blessed be He, said, "Abraham used to feed fetuses and wayfarers, and Esau came and killed them, and he used to fill the caves with corpses, and Jezebel used to kill the prophets. Obadiah hid them in caves and sustained them, as it says, 'And it was when Jezebel was cutting off the prophets of the Lord, Obadiah took a hundred prophets and hid them in fifty caves and sustained them with bread and water' (1 Kings 18:4). The Holy One, blessed be He, said, 'Let Obadiah come, who fed the prophets in caves, and punish Esau, who killed people in caves.' Therefore it is said, 'The vision of Obadiah.' Another commentary: Esau circumcised his fathers, but he despised the circumcision and chose to remain uncircumcised. Obadiah, on the other hand, was uncircumcised and despised it, but he chose to be circumcised. The Holy One, blessed be He, said, 'Let Obadiah come, who despised circumcision and circumcised himself, and punish Esau, who circumcised his fathers and made himself uncircumcised.' Therefore it is said, "The vision of Obadiah." Another commentary: Esau sought to fulfill the wishes of his father, as it says, 'And Esau said in his heart, "Let the days of mourning for my father draw near"' (Genesis 27:41), but Obadiah honored one who was not his father, as it says, 'And behold, Obadiah was on the way, and Elijah met him, and he recognized him and fell on his face...' (1 Kings 18:7). The Holy One, blessed be He, said, 'Let Obadiah come, who honored one who was not his father, and punish Esau, who sought the death of his father.' [Obadiah 1:21] Therefore it is said, 'The vision of Obadiah, but for Israel, I have known his thoughts...' (Jeremiah 29:11).