Hebrews 1:3
“He sat” (says he) “on the right hand of the Majesty on high.” What is this “on high”? Does he enclose God in place? Away with such a thought! But just as, when he says, “on the right hand,” he did not describe Him as having figure, but showed His equal dignity with the Father; so, in saying “on high,” he did not enclose Him there, but expressed the being higher than all things, and having ascended up above all things. That is, He attained even unto the very throne of the Father: as therefore the Father is on high, so also is He. For the “sitting together” implies nothing else than equal dignity. But if they say, that He said, “Sit,” we may ask them, What then? Did He speak to Him standing? Moreover, he said not that He commanded, not that He enjoined, but that “He said”: for no other reason, than that you might not think Him without origin and without cause. For that this is why he said it, is evident from the place of His sitting. For had he intended to signify inferiority, he would not have said, “on the right hand,” but on the left hand.
Source: Homilies on the Epistle to the Hebrews (New Advent)