Midrasch zu Jirmejahu 51:9

Our Rabbis were taught: Naaman was a Ger Toshab. Nebusaradan, however, was a true proselyte; from the descendants of Sissera were those who studied the law in Jerusalem, and from the descendants of Sennacherib were those who taught the Torah among the multitudes of Israel, and they are Shmayah and Abtalion. From the descendants of Haman were those who learned the Torah in the city of Bnei-Brack, and this is R. Samuel b. Shiloth. And even the descendants of Nebuchadnezzar, it was the intention of the Holy One, praised be He! to take under the Divine protection. But the angels said before Him: "Sovereign of the Universe, he who has destroyed your house, burned your Temple, shouldst Thou take him under the protection of the Shechinah?" This is meant by the passage (Jer. 51, 9) We would have healed Babylon, but she was not healed. Ula said: "This refers to Nebuchadnezzar." Samuel b. Nachman, however, said: "This refers to the Babylonian rivers." And it was explained that he meant the palms of Babylonia.