The term "The Ancient of Days" appears three times in the Book of Daniel and is used in the sense of God being eternal.
"I beheld till the thrones were cast down, and the Ancient of Days did sit, whose garment was white as snow, and the hair of his head like the pure wool: his throne was like the fiery flame, and his wheels as burning fire." (Daniel 7:9)
"I saw one like a human being coming with the clouds of heaven. And he came to the Ancient One and was presented before him. To him was given dominion and glory and kingship, that all peoples, nations, and languages should serve him. His dominion is an everlasting dominion that shall not pass away, and his kingship is one that shall never be destroyed." (Daniel 7:13-14)
The Jewish sages understand "Daniel 7:13" as the coming of the Messiah:
Rashi on Daniel 7:13
"one like a man was coming That is the King Messiah."
"Rabbi Alexandri says: Rabbi Yehoshua ben Levi raises a contradiction between two depictions of the coming of the Messiah. It is written: “There came with the clouds of heaven, one like unto a son of man…and there was given him dominion and glory and a kingdom…his dominion is an everlasting dominion” (Daniel 7:13–14). And it is written: “Behold, your king will come to you; he is just and victorious; lowly and riding upon a donkey and upon a colt, the foal of a donkey” (Zechariah 9:9). Rabbi Alexandri explains: If the Jewish people merit redemption, the Messiah will come in a miraculous manner with the clouds of heaven. If they do not merit redemption, the Messiah will come lowly and riding upon a donkey."
Both Rabbi Alexandri and Rabbi Yehoshua ben Levi interpreted (Daniel 7:13–14) as a reference to a possible miraculous coming of the messiah to the Jewish people...
How can such interpretation be reconciled with the text of Daniel itself that describes "one like a son of man" (the messiah, who will be born and live on earth according to the Jewish sages) coming on a cloud to God who is sitting on his throne in heaven a scene which suggests the Messiah's ascension to heaven and not the opposite (the Messiah will come to the Jewish people in a miraculous manner with the clouds of heaven)?