Midrasch zu Tehillim 73:25

31...From whence did Israel merit to recite the shema? Rabbi Pinhas ben Hama said: [Israel merited to recite the shema] at the Revelation on Sinai. How [is this to be inferred]? You find that it was not with “I am the ETERNAL thy God,” and all answered; The Holy One, blessed Be, began at Sinai rather with this word, saying to them: “Hear, O Israel, I am the ETERNAL thy God,”and they all answered and exclaimed: “ The ETERNAL our God, the ETERNAL is one.” And Moses said, “Blessed be the name of God”s glorious kingdom for ever and ever.” Our rabbis said: “The Holy One blessed Be, said to Israel: ‘ My children, all that I created, I created in pairs: heaven and earth are a pair, sun and moon are a pair, Adan and Eve are a pair, this world and the world to come, a pair, but my Glory is one and unique in the world.” Accordingly, from our declaring regarding: “Hear O Israel, the ETERNAL is our God the ETERNAL is One.”

(Numb. 19:2, cont.:) ON WHICH THERE HAS BEEN NO YOKE. This is Edom (i.e., Rome), since they never took upon themselves the yoke of the Holy One. Moreover, it was not enough for them not to accept it, but they slander and blaspheme by saying (in Ps. 73:25): WHOM DO I HAVE IN HEAVEN…?