Midrasz do Estery 9:24

Rabbi Phineas said: The Holy One, blessed be He, saw that in the future there would arise from Agag a man, a great enemy and adversary of the Jews. Who was this? This was Haman, as it is said, "Because Haman, the son of Hammedatha, the Agagite, the enemy of all the Jews" (Esth. 9:24). From the seed of Saul (arose) an avenger and a redeemer for Israel, (who delivered them) out of the hand of Haman. Who was this? This was Mordecai, as it is said, "There was a certain Jew in Shushan, the capital, whose name was Mordecai… the son of Kish, a Benjamite" (Esth. 2:5).